Physics 105 - How Things Work

Problem 1:

The outside temperature is 0 °F (-18 °C) and there is snow on the ground. Oddly enough, the snow is gradually disappearing into the air. The snow is disappearing because

(A) while water molecules are both landing on and leaving the snow's surface, they are landing more often than they are leaving.

(B) water molecules release potential energy as they separate into a gas, so the need to reduce total potential energy causes the snow to convert into water vapor.

(C) there is always liquid water present when both solid ice and gaseous water vapor exist. The ice is becoming water and the water is evaporating as water vapor.

(D) while water molecules are both landing on and leaving the snow's surface, they are leaving more often than they are landing.

Problem 2:

Copper is a much better conductor of heat than glass because copper

(A) contains mobile electrons while glass does not.

(B) has a reddish color while glass is transparent.

(C) is much softer than glass.

(D) is shiny and reflective while glass is not.

Problem 3:

As the wind blows past one of the entry doors to a modern office building, the wind is bending inward—toward the building's surface. This entry door can swing either inward (into the building) or outward (out of the building). The effect of the wind is to make it

(A) easy to open the door outward and hard to open it inward.

(B) hard to open the door outward and easy to open it inward.

(C) easy to open the door both outward and inward.

(D) hard to open the door both outward and inward.

Problem 4:

A stream is flowing gently under a bridge and past a cylindrical support post. The flow around this vertical post is smooth and laminar, so the water separates in front of the post, arcs around its sides, and rejoins behind the post before continuing down the stream. Compared with the average water level in the stream, the water level is

(A) high in front of the post and low on the sides and behind the post.

(B) high in front of and behind the post, and low on the sides of the post.

(C) low in front of the post and high on the sides and behind the post.

(D) low in front of and behind the post, and high on the sides of the post.

Problem 5:

Two cars are heading northward on a highway. The red car is in front and the blue car is behind it. The blue car gently bumps the red car and the two cars push on one another and exchange momentum. The force that the blue car exerts on the red car is

(A) equal in amount to the force the red car exerts on the blue car and the momentum lost by the blue car is equal to the momentum gained by the red car.

(B) larger in amount than the force the red car exerts on the blue car, but the momentum lost by the blue car is equal to the momentum gained by the red car.

(C) equal in amount to the force the red car exerts on the blue car, but the momentum lost by the blue car is greater than the momentum gained by the red car.

(D) smaller in amount than the force the red car exerts on the blue car, but the momentum lost by the blue car is equal to the momentum gained by the red car.

Problem 6:

While the strings of a violin or guitar are all the same length, the strings in a piano get shorter as their pitch (frequency) increases. The highest frequency strings of a piano are only a few inches long. But suppose the strings of a piano were all the same long length. To compensate from their dramatic increase in length, those highest frequency strings would have to have

(A) more tension and less mass per inch.

(B) more tension and more mass per inch.

(C) less tension and less mass per inch.

(D) less tension and more mass per inch.

Problem 7:

A rocket is heading upward quickly and a plume of exhaust is streaming downward from its tail. The amount of force that the rocket is exerting on the plume of exhaust is

(A) less than the amount of force the plume is exerting on the rocket, but not zero.

(B) greater than the amount of force the plume is exerting on the rocket.

(C) equal to the amount of force the plume is exerting on the rocket.

(D) zero.

Problem 8:

It's a cold winter day and you are in an unheated cabin in the woods. Everything in the cabin is at the same cold temperature. You find that when you stand in front of a full-length mirror in the bedroom that you feel warmer. That is because the mirror

(A) emits more of its own thermal radiation at you than any other surface in the house.

(B) concentrates the thermal radiation from the rest of the bedroom and focuses it on you.

(C) reflects your own thermal radiation back at you, so you lose heat more slowly.

(D) emits less of its own thermal radiation at you than any other surface in the house.

Problem 9:

A single violin string can vibrate in several different ways, as though it were several separate harmonic oscillators. Each of these vibrational modes has its own frequency. If the frequency of the fundamental (lowest frequency) vibrational mode is 440 Hz (Hertz or cycles-per-second), then the frequencies of the string's overtones are

(A) 880 Hz, 1320 Hz, 1760 Hz, and so on.

(B) 880 Hz, 1760 Hz, 3520 Hz, and so on.

(C) 550 Hz, 660 Hz, 770 Hz, and so on.

(D) 660 Hz, 880 Hz, 1100 Hz, and so on.

Problem 10:

Gliders often have very long wings so that they contact lots of air each second. These long wings enable the glider to stay aloft longer because it can then give the air it contacts

(A) large amounts of downward momentum and energy.

(B) a large amount of downward momentum but a small amount of energy.

(C) small amounts of downward momentum and energy.

(D) a small amount of downward momentum but a large amount of energy.

Problem 11:

When a sport utility vehicle (SUV) makes a sudden left turn on the highway, it is in danger of flipping over. One valid explanation for this effect is:

(A) the SUV's angular mass increases as it turns and its angular momentum decreases. A transfer of angular momentum from its wheels to its frame then causes it to begin rotating so that it flips over.

(B) the centrifugal force on the SUV as it goes around the turn pushes outward on the top of the SUV. The wheels are held in place by friction, so only the top of the SUV accelerates outward and it flips over.

(C) the leftward frictional force that causes the SUV to accelerate leftward during the turn also exerts a torque on the SUV about its center of mass and can cause the SUV to undergo angular acceleration and flip over.

(D) the force of the SUV's momentum pushes it forward while the road pushes it to the left and these two forces twist the SUV so that it undergoes angular acceleration and flips over.

Problem 12:

As an incandescent light bulb ages, it develops a dark spot on the glass directly above the filament. This dark spot indicates that the bulb has gas inside it because the spot is produced by

(A) plasma.

(B) conduction.

(C) convection.

(D) radiation.

Problem 13:

You're a passenger in a car and you have your eyes closed. The car is traveling at a constant speed on a level road that is turning toward the left. You feel a gravity-like sensation toward your right, but you remain in your car seat. The net force acting on you during this turn

(A) is zero.

(B) points toward your left.

(C) points toward your right.

(D) points forward.

Problem 14:

A plastic bottle, partly full of water, has been sitting on the kitchen counter for the past hour. Some of the water molecules in the bottle are gaseous and some are liquid. To increase the amount of liquid water in the bottle, you could (note: neglect any effect squeezing has on the temperatures in the bottle)

(A) cool the bottle down, but you must not squeeze it to increase the density of its gas.

(B) open the bottle to the kitchen air.

(C) cool the bottle down and/or squeeze it to increase the density of its gas.

(D) warm the bottle up and/or squeeze it to increase the density of its gas.

Problem 15:

To make a large surface wave on the ocean travel faster, you could

(A) increase its amplitude (the height difference between its crests and troughs).

(B) decrease its amplitude (the height difference between its crests and troughs).

(C) decrease its wavelength (the distance between adjacent crests).

(D) increase its wavelength (the distance between adjacent crests).

Problem 16:

To catch a football successfully, you should allow the ball to push your hands in the direction of its travel. Allowing your hands to move with the football is crucial because it allows you to

(A) add energy to the football.

(B) add momentum to the football.

(C) extract momentum from the football.

(D) extract energy from the football.

Problem 17:

As you are going around the loop-the-loop on a roller coaster, you are basically traveling in a vertical circle. For simplicity, let's imagine that you are traveling around and around that circle. When during this circular motion do you feel the heaviest?

(A) When you are at the bottom of the circle.

(B) When you are going down the descending side of the circle.

(C) When you are going up the rising side of the circle.

(D) When you are at the top of the circle.

Problem 18:

You drop a bouncy ball from rest and it bounces off a granite floor. The ball rebounds to its original height. During the bounce, the ball transferred

(A) both energy and momentum to the floor.

(B) neither energy nor momentum to the floor.

(C) energy but not momentum to the floor.

(D) momentum but not energy to the floor.

Problem 19:

You are standing still in the basket of a hot air balloon and you are wearing a backpack. As the hot air balloon rises upward, you are doing

(A) (positive) work on the backpack and the hot air balloon is doing zero work on you.

(B) (positive) work on the backpack and the hot air balloon is doing (positive) work on you.

(C) zero work on the backpack and the hot air balloon is doing zero work on you.

(D) zero work on the backpack and the hot air balloon is doing (positive) work on you.

Problem 20:

You are swinging a bucket full of water around you in a big horizontal circle at a constant speed. You are at the center of its circular path. The net force on the bucket points directly

(A) toward you.

(B) downward.

(C) along the bucket's velocity (along its direction of travel).

(D) away from you.

Problem 21:

A guitar string vibrating in its fundamental mode (as a single arc) behaves as a harmonic oscillator, which means that the restoring force acting on the string is

(A) proportional to how far it is from equilibrium and that its pitch (frequency) can vary but its volume (amplitude) cannot.

(B) proportional to how far it is from equilibrium and that its volume (amplitude) can vary but its pitch (frequency) cannot.

(C) independent of how far it is from equilibrium and that its volume (amplitude) can vary but its pitch (frequency) cannot.

(D) independent of how far it is from equilibrium and that its pitch (frequency) can vary but its volume (amplitude) cannot.

Problem 22:

You are at a campfire in an open field. It is a cool, windless evening and you are sitting 10 feet from the fire. The fire is keeping you warm by transferring heat to you via

(A) radiation alone.

(B) conduction alone.

(C) conduction and convection.

(D) radiation and convection.

Problem 23:

A kitchen mixer combines the ingredients best when its blades turn fairly rapidly through the batter you are making. If the blades turn too slowly, the various ingredients don't mix thoroughly, even if you wait a considerable amount of time. The advantage of rapid motion of the mixer blades reflects the need for

(A) inertia to dominate the flow of batter in the mixer, so that the resulting turbulent flow can fully combine the ingredients.

(B) inertia to dominate the flow of batter in the mixer, so that the resulting laminar flow can fully combine the ingredients.

(C) viscosity to dominate the flow of batter in the mixer, so that the resulting turbulent flow can fully combine the ingredients.

(D) viscosity to dominate the flow of batter in the mixer, so that the resulting laminar flow can fully combine the ingredients.

Problem 24:

If you use a microwave oven to heat clean water in a smooth glass container, you can sometimes superheat the water—that is, raise its temperature well above water's boiling temperature without it boiling. In that case, the very hot water fails to boil because

(A) even though bubbles of pure steam are stable at such high temperatures, they cannot form without help.

(B) bubbles of pure steam must stick to the surface of a container in order to grow in size, but slick glass surfaces won't hold these bubbles in place long enough for boiling to occur.

(C) bubbles of pure steam are not stable in clean water that is uniformly heated, even at such high temperatures.

(D) bubbles of pure steam shrink quickly when they are exposed to atmospheric pressure, even at such high temperatures.

Problem 25:

You and your best friend are trying to pull one another toward your respective dorm rooms. You're the stronger of the two and, with a mighty tug, you drag your friend into your room. As you are pulling your friend toward your room, the force you exert on your friend is

(A) equal in amount to the force your friend exerts on you.

(B) definitely equal to three times the weight of Spongebob Squarepants.

(C) less in amount than the force your friend exerts on you.

(D) greater in amount than the force your friend exerts on you.

Problem 26:

A steam engine manages to do real work using only hot steam and cold air. It needs both the steam and the air because

(A) there is order present in their difference in temperature.

(B) total entropy decreases when heat flows spontaneously from hot steam to cold air.

(C) work is released when heat flows from cold air to hot steam.

(D) there is order present in the hot steam and energy present in the cold air.

Problem 27:

At the heart of a quartz watch is a tiny

(A) quartz sphere that bounces about like a ball in a box.

(B) container of quartz powder that emits electrical pulses because of thermal energy.

(C) quartz sphere that spins with constant angular acceleration.

(D) quartz tuning fork that vibrates like a pair of masses on a spring.

Problem 28:

Because of bad planning during the design and construction of a high-rise apartment building, all 50 floors of the building receive their water from a single pipe. That pipe is fed from a water tank located on the building's roof. On opening day, residents on various floors begin taking showers and have different experiences. They quickly discover that the total energy per liter in the spraying water is (neglecting any effects of viscosity and friction)

(A) less on higher floors

(B) greater on higher floors.

(C) the same on all floors, but the speed of the spraying water is slower on higher floors.

(D) the same on all floors, but the speed of the spraying water is higher on higher floors.

Problem 29:

Tides are caused by the moon's gravity acting on the earth and its oceans. The moon reshapes the earth's oceans so that they bulge slightly outward

(A) only on the side of the earth closest to the moon.

(B) all the way around the earth, from north pole to south pole.

(C) on the side of the earth closest to the moon and the side of the earth farthest from the moon.

(D) all the way around the earth's equator.

Problem 30:

Before it burns the fuel and air mixture, the piston and cylinder of an automobile engine compress that mixture to high density. During this compression, the temperature of the mixture rises because

(A) the piston does work on the mixture during the compression process.

(B) friction between the piston and cylinder heats the mixture.

(C) high density gases are hotter than low density gases.

(D) high pressure gases are hotter than low pressure gases.

Problem 31:

You cannot cool room air simply by converting its thermal energy into electrical energy because

(A) that would be a statistically unlikely event.

(B) that would violate Newton's third law of motion.

(C) that would violate Newton's second law of motion.

(D) thermal energy and electrical energy are different conserved quantities and one cannot be converted into the other.

Problem 32:

You are bouncing gently up and down at the end of a springy diving board, with your feet never leaving its surface. If you double the overall height of the bounce, the time it takes to complete each bounce (the period of the bounce) will

(A) increase by a factor of 4.

(B) decrease by a factor of 2.

(C) stay the same.

(D) increase by a factor of 2.

Problem 33:

The pendulum of a grandfather clock gradually loses energy because of air drag and friction. To keep its pendulum swinging, the clock has to add a tiny amount of energy to it every swing. In essence, the clock gently pushes the pendulum in the

(A) same direction as its acceleration.

(B) same direction as its velocity.

(C) direction opposite its acceleration.

(D) direction opposite its velocity.

Problem 34:

The air emerging from the nozzle of a leaf blower is traveling fast but its pressure is atmospheric pressure. Before that same air passed through the nozzle it was traveling

(A) faster but its pressure was above atmospheric pressure.

(B) slower but its pressure was below atmospheric pressure.

(C) slower but its pressure was above atmospheric pressure.

(D) faster but its pressure was below atmospheric pressure.

Problem 35:

A huge abstract iron sculpture has been installed in front of the local art museum. It sits there motionless, "guarding" the main doorway. The sculpture is experiencing its weight downward and an equally strong force upward from the brick courtyard beneath it. We know that these two forces on the sculpture are equal in amount but oppositely directed because

(A) for every action, there is an equal but oppositely directed reaction.

(B) the sculpture is not accelerating so the two forces must sum to zero.

(C) the sculpture has zero velocity.

(D) Newton's third law requires that forces always appear in equal but oppositely directed pairs.

Problem 36:

You drop a bouncy ball straight down from your friend's 30th floor balcony. It is spinning rapidly so that its northern side is turning upward (toward you). As a result of this spin, the ball does not continue falling straight downward, but instead deflects horizontally as it falls. The ball deflects the passing airstream

(A) northward and the ball accelerates northward.

(B) southward and the ball accelerates southward.

(C) southward and the ball accelerates northward.

(D) northward and the ball accelerates southward.

Problem 37:

When a large wave travels across the ocean, water at the ocean's surface moves

(A) steadily forward at the wave's velocity.

(B) steadily forward at half the wave's velocity.

(C) directly up and down and returns to its starting point.

(D) in a circular path and returns to its starting point.

Problem 38:

You toss a quarter straight up into the air. It rises to a peak and then descends. After it leaves your hand and neglecting air resistance, the quarter experiences

(A) a downward net force that is proportional to the quarter's speed.

(B) a constant downward net force.

(C) an upward net force that gradually diminishes to zero at its peak height and then becomes a downward net force.

(D) a constant upward net force on the way up and a constant downward net force on the way down.

Problem 39:

The light from an incandescent light bulb is redder than sunlight and photographs taken in incandescent lighting often have a reddish cast to them. There is a practical reason why an incandescent light bulb cannot produce a larger fraction of blue light. To shift its light spectrum toward the blue, the bulb would have to

(A) shorten the distance between coils in its spiral filament and no one knows how to wind these tiny spirals any tighter.

(B) use a blue metal filament and all known metals are either shiny, yellow, orange, or red.

(C) increase the length of its filament and the filament would consume too much electricity to be cost effective.

(D) operate its filament at a higher temperature and the filament would die quickly.

Problem 40:

You roll a marble down the side of a round bowl—a bowl with a spherical bottom. The marble rolls back and forth between the front and back of the bowl, passing right through the bottom of the bowl on each trip. At this exact moment, the marble has just rolled down your side of the bowl and is exactly at the bottom of the bowl. It is about to begin rolling up the far side of the bowl. It is accelerating

(A) away from you.

(B) upward.

(C) downward.

(D) toward you.

Problem 41:

Two marbles are in a large bowl and the system is completely isolated from its surroundings. Each of the four arrangements listed below as possible answers contains exactly the same amount of total energy, although that energy may be in different forms in the different arrangements. Which arrangement has the most entropy:

(A) the marbles high up on the same side of the bowl, but not touching.

(B) the marbles both rolling quickly through the bottom of the bowl, but not touching.

(C) the marbles resting motionless in the bottom of the bowl.

(D) the marbles high up on opposite sides of the bowl.

Problem 42:

If you throw a ball straight forward at high speed with no spin at all, the air pressure at its surface will not be uniform. The location of the highest air pressure on the ball's surface will be at its

(A) front (the side farthest from you).

(B) bottom.

(C) top.

(D) back (the side nearest to you).

Problem 43:

When you blow gently across the top of a soda bottle, the air inside it vibrates as a harmonic oscillator and it emits a clear tone. If you replace the air in the bottle with helium, the bottle's new tone will definitely occur at a

(A) lower pitch (a lower frequency).

(B) lower volume (a smaller amplitude).

(C) higher pitch (a higher frequency).

(D) higher volume (a larger amplitude).

Problem 44:

A liquid pours smoothly down a channel and into a basin, experiencing only laminar flow. To make this flow become turbulent, you should

(A) decrease the speed of the flow and/or decrease the viscosity of the liquid.

(B) increase the speed of the flow and/or increase the viscosity of the liquid.

(C) increase the speed of the flow and/or decrease the viscosity of the liquid.

(D) decrease the speed of the flow and/or increase the viscosity of the liquid.

Problem 45:

Two children are trying to lift toys using identical-looking helium balloons. However, one child is located in Norfolk, where the altitude is roughly sea level, and the other child is located in Denver, where the altitude is about 5,000 feet above sea level. Which balloon, if any, can lift more weight?

(A) I am just randomly picking answers and do not deserve credit for this problem.

(B) The Denver balloon can lift more weight.

(C) They can both lift equal weights.

(D) The Norfolk balloon can lift more weight.

Problem 46:

A wooden sculpture weighs exactly 1 pound. You very gently float this sculpture in a pot that was perfectly full of water, so some of that water overflows. The pot is again perfectly full of water, but now the sculpture is floating in it. If you weigh the water that overflowed, you'll find that it weighs

(A) slightly less than 1 pound.

(B) much less than 1 pound.

(C) exactly 1 pound.

(D) more than 1 pound.

Problem 47:

You're standing at the top of a tall lighthouse. You are holding two balls, one twice as heavy as the other, and you throw them together horizontally with one hand. They leave your hand at the same time and the same speed. Both balls soon hit the water. Neglecting any air resistance, the heavier ball reaches the water

(A) at the same time but half as far from the lighthouse as the lighter ball.

(B) in half the time and half as far from the lighthouse as the lighter ball.

(C) in half the time but at the same place as the lighter ball.

(D) at the same time and at the same place as the lighter ball.

Problem 48:

An air conditioner is most effective at cooling a room on a warm summer day when the work done while operating its compressor ends up as

(A) thermal energy split evenly between the outside air and the indoor air.

(B) thermal energy in the indoor air.

(C) work back at the power company.

(D) thermal energy in the outside air.

Problem 49:

A high-speed chase ends when the robbers drive their car into the concrete base of a bridge. The car is badly crumpled and the robbers are dazed, but the bridge is unscathed. When the car collided with the bridge, it transferred

(A) both momentum and energy to the bridge.

(B) momentum to the bridge but did not transfer energy to the bridge.

(C) neither momentum nor energy to the bridge.

(D) energy to the bridge but did not transfer momentum to the bridge.

Problem 50:

A kiln is used to fire pottery—to heat it red or even yellow hot so that it fuses into a hard, finished ceramic. You have four pots to fire, each with its own surface color. One is black, one is white, one is shiny aluminum-like, and one is essentially transparent. You place the four pots in a kiln and heat them to the same yellow-hot temperature. When you look inside the kiln, the one that is glowing most brightly is the one that is

(A) white.

(B) shiny aluminum-like.

(C) black.

(D) essentially transparent.

PART II: SHORT ANSWER QUESTIONS

Please give a brief answer in the space provided. Part II is worth 33% of the grade on the examination.

Problem 1:

You are trying to learn how to walk on a tightrope. The rope stretches between two rigid supports and has a net below it to catch you each time you fall of the rope. Needless to say, you and the net have encountered each other a great many times.

(A) When you are standing exactly upright on the rope, you are in equilibrium. And when you hang from the rope with your hands, you are also in equilibrium. Why is it so much easier to stay in the hanging equilibrium than the standing equilibrium?

(B) What happens to your total potential energy whenever you begin to tip away from the standing equilibrium?

(C) To help you stay in the standing equilibrium, you hold a long massive rod by its middle. Each time you begin to tip over toward the right, you twist the rod hard so that its right end drops and its left end rises. The rod responds by twisting you back toward the standing equilibrium. What conserved physical quantity are you exchanging with the rod when you use it in this manner?

(D) After a while, you get so good at tightrope walking that you start bouncing as you walk. As long as you stay in contact with the rope, the period of each bounce is independent of how far you bounce. But when you start bouncing so high that your feet lose contact with the rope, the period starts to get longer. Why is the period dependent on how far you bounce once your feet begin to leave the rope?

Problem 2:

When you look out your apartment window, you can see a power line that stretches between two utility poles. On a windy day, you notice that the line is bouncing up and down rhythmically as a single arc, once per second—its fundamental period.

(A) A flock of birds settles on the line. Do these birds affect the fundamental period and, if so, does that period increase or decrease?

(B) The birds have left and you continue to watch the power line. You notice that it sometimes bounces as a single arc and sometimes bounces as two halves—half the line arcs upward as the other half arcs downward. What is the period of this second mode of bouncing—its overtone period? Be specific.

(C) The utility company arrives and tightens the power line. Does this increase in the line's tension affect its fundamental period and, if so, does that period increase or decrease?

(D) Finally, the utility company clips a large mass to the power line, exactly midway between the two utility poles, while leaving the line's tension unchanged. Does the presence of this mass affect either period (fundamental and/or overtone) and, if so, does that period(s) increase or decrease?

Problem 3:

There's nothing like skydiving to get the adrenaline running! You have just jumped out of a plane at 15,000 feet and you're plummeting toward the ground.

(A) Your friend pushed on your shoulder as you left the plane and set you spinning about a vertical axis. You are having trouble stopping the spin. What conserved quantity are you trying to transfer to the air in order to stop spinning?

(B) You have stopped spinning and have reached terminal velocity: you are descending in a straight vertical line at a constant velocity. The only significant upward force you are experience is pressure drag. What is the amount of that drag force?

(C) You are now trying to get together with your friends, who are above you and to your north. To join your friends in the vertical direction, you spread out your arms and increase the drag force you experience. Why does that help reduce your vertical separation from your friends?

(D) To join your friends in the horizontal direction, you begin to push the passing air toward the south. Why does that help reduce your horizontal separation from your friends?

Problem 4:

When an air conditioner is operating properly, its working fluid converts back and forth between a gas and a liquid. The fluid converts from a gas to a liquid in the condenser located outside. The fluid converts from a liquid to a gas in the evaporator located inside.

(A) Both liquid and gaseous working fluid are present in the condenser. However, to encourage the working fluid to convert from a gas to a liquid there, the air conditioner increases the density of that gas. Why does increasing the density of the gas favor the formation of liquid working fluid?

(B) As the working fluid condenses from a gas to a liquid, it releases an enormous amount of thermal energy even when its temperature doesn't change. What form of energy was it that was converted into this thermal energy?

(C) As the liquid working fluid evaporates into the vast, nearly empty chamber of the evaporator, its temperature drops. The working fluid and chamber therefore lose thermal energy so the entropy associated with thermal energy in the evaporator decreases. Nonetheless, the second law of thermodynamics is not being violated because entropy associated with something else is being created during the evaporation. What order is being lost as the liquid evaporates?

(D) Both the indoor air and the outdoor air experience changes in their entropies while the air conditioner is operating. (1) Does the entropy of the indoor air increase or decrease? (2) Does the entropy of the outdoor air increase or decrease? (3) Which of the two experiences the larger change in entropy, or are they equal in amount?

Problem 5:

A bird is flying at constant velocity in a straight, horizontal path at an altitude of 1,000 feet.

(A) What is the net force on the bird?

(B) Gravity is transferring a certain amount of downward momentum to the bird every second. How do we know this?

(C) The bird is not accumulating any net downward momentum. What is it doing with the downward momentum that gravity is transferring to it?

(D) The bird is experiencing pressure drag as it flies forward. This pressure drag pushes the bird backward. What does the bird do to keep from slowing down? (No details, just the basic physics please… a dozen words should be enough.)

Problem 6:

A tall flagpole sits motionless and perfectly upright on a calm summer day. Suddenly, a flying Frisbee hits the flagpole hard near its top and it begins swaying back and forth rhythmically, toward you and away from you. Let's neglect air resistance or any forms of friction, so the flagpole will sway like this forever.

(A) When during its swaying is the flagpole accelerating toward you the fastest?

(B) When during its swaying is the flagpole moving toward you the fastest? (i.e. has its maximum velocity toward you.)

(C) When during its swaying does the flagpole have its lowest amount of total potential energy?

(D) When during its swaying does the flagpole have its largest amount of momentum toward you?