Please mark the correct answer for each question on the bubble
sheet. Fill in the dot completely with #2 pencil. Part I is worth 67% of the
grade on the midterm examination.
When a car "knocks," that is because the fuel and
air mixture in one of its cylinders is igniting before the spark plug fires.
This early ignition occurs because compressing the mixture causes its
Viscous drag is associated with viscose forces within the
air, while pressure drag is associated with unbalanced pressures. When a dust
particle in the air is experiencing only gravity, it descends very slowly through
the air around it. Because of its tiny size and slow motion, the dust particle
experiences
When you bounce up and down on a springboard, without leaving
the board's surface, you are a harmonic oscillator. But as soon as you fly up
off the surface, you stop being a harmonic oscillator because
During the power stroke in one cylinder of a car's engine,
the burned fuel and air gases push the piston out of the cylinder. In accordance
with Newton's third law, the piston pushes back on the burned gases. Overall,
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
The bottom of a large hot-air balloon is open, yet the hot
air doesn't flow out. That is because
Your company has invented a new rubber ball that bounces perfectly.
When you drop it on a hard surface, it rebounds to its original height and continues
to bounce that way indefinitely. This phenomenal bounciness indicates that the
ball
When a log is floating on water, much of the log is above
the water and is actually surrounded by air. If that surrounding air were to
suddenly be replaced by an oil that is less dense than the log, the log would
You travel quickly around the loop-the-loop of a roller coaster
and find that you can't even tell when you are upside-down without looking.
At the very top of the loop, you are
A 1-inch (2.5 cm) diameter garden hose will carry far more
water than a 1/2-inch (1.25 cm) diameter garden hose, everything else being
equal. This phenomenon is explained by the fact that the wider hose
When hurricane winds blow horizontally past the peaked or
domed roof of a house, they tend to lift that roof upward and pull it off the
house. This upward force develops because the airflow bends downward (toward
the roof) as it flows over the top of the roof. This downward bend (toward the
roof's upper surface) indicates that the air pressure at the roof's upper surface
is
You throw a ball at the wall in front of you and the ball
bounces directly back at you. While the ball is touching the wall, the horizontal
force(s) the ball is experiencing is (are)
A helium-filled balloon weighs only about 1/7th as much as
the air it displaces. If you replace the helium gas in the balloon with hydrogen
gas (which is half as dense as helium gas), the upward buoyant force on the
balloon would
The houseware store you have just entered has a uniform temperature
throughout. You pick up a heavy copper pot and place it on a soft, fabric mat.
As a result of this contact, heat
A friend suggests that you invest in a new invention that
apparently absorbs heat from the room and converts it into electricity. It supposedly
sits in the middle of the room, gradually cooling the room air while providing
a steady and endless supply of electric power. You wisely choose not to invest
because in order to work as described, this device would have to do something
impossible-it would have to
You are choosing the filament for a light bulb and want it
to emit visible light as efficiently as possible when it becomes very hot. You
should make that filament
A turbofan engine includes a giant ducted fan-a fan that sits
inside a duct. The purpose of this huge metal duct is to slow the passing air
down so that the fan doesn't have to work with air moving by at the full speed
of the airplane. Instead of dealing with air moving at 600 mph, the air passing
through the duct may be traveling only 200 mph. The duct slows the passing air
primarily by
Sound waves in air and surface waves on water differ in the
following important respect:
(A) sound waves in air have frequencies, while surface
waves on water do not have frequencies.
(B) the speed of sound waves in air doesn't depend on
frequency, while the speed of surface waves on water does depend on frequency.
(C) sound waves in air do not have wavelengths, while
surface waves on water do have wavelengths.
(D) sound waves in air are standing waves, while
surface waves on water are traveling waves.
Answer: (B) the speed of sound waves in air doesn't
depend on frequency, while the speed of surface waves on water does depend
on frequency.
Why: All sound waves travel at the same speed, so music
sounds the same at any distance from the source. Water surface waves travel
at different speeds (lower frequency waves travel fastest).
Problem 21:
Two children are swinging on identical swings. One child
is twice as heavy as the other. The period of the lighter child's swing is
(A) about 3/4 the period of the heavier child's
swing.
(B) about twice the period of the heavier child's swing.
(C) about half the period of the heavier child's swing.
(D) about the same as the period of the heavier child's
swing.
Answer: (D) about the same as the period of the heavier
child's swing
Why: The mass of the pendulum doesn't matter. A larger
mass may increase the pendulum's inertia, but it also increases the restoring
force. The two increases exactly cancel.
Problem 22:
You are outside the shuttle on a routine satellite repair
mission. You are moving at a constant speed at a constant distance of two
earth radii above the surface of the earth. Relative to your weight on the
surface of the earth, what is the magnitude of the net force on you? Neglect
the effects of the satellite and the shuttle.
(A) zero
(B) 1/2
(C) 1/4
(D) 1/9
Answer: (D) 1/9
Why: You are now 3 times as far from the center of the
earth as you would be on the ground, so the force of gravity is diminished
by a factor 9 (the square of 3).
Problem 23:
Wrapping a hot potato in aluminum foil will help keep the
potato warm because the shiny aluminum foil
(A) is a very poor emitter of thermal radiation.
(B) is so thin that it doesn't have enough mass to cool
the potato significantly.
(C) is transparent to infrared radiation and allows radiant
heat from the room to enter the potato and keep it warm.
(D) is a poor conductor of heat, so the surface temperature
of the foil is much less than the surface temperature of the potato.
Answer: (A) is a very poor emitter of thermal radiation.
Why: Shiny aluminum reflects the surrounding thermal radiation,
rather than emitting its own.
Problem 24:
You're operating a propane gas grill from a fuel tank that's
located below the grill. This tank is half filled with liquid propane. As
the grill consumes gaseous propane, the tank's temperature drops below room
temperature. This refrigerating effect occurs because
(A) heat naturally flows from a cooler object to
a hotter object.
(B) heat is needed to initiate and sustain combustion
in the grill.
(C) thermal energy is being used to convert liquid propane
into gaseous propane in the tank.
(D) heat naturally rises from the tank to the grill
above it.
Answer: (C) thermal energy is being used to convert
liquid propane into gaseous propane in the tank.
Why: Separating the bound propane molecules in liquid
propane into individual gas molecules takes energy and that energy is taken
out of the liquid propane's thermal energy. It's temperature drops as a
result.
Problem 25:
The glass envelope of an ordinary incandescent light bulb
surrounds a
(A) volume of chemically inert gas, which significantly
increases the bulb's energy efficiency but slightly shortens the filament's
life expectancy.
(B) region of almost perfect vacuum, which significantly
increases the bulb's energy efficiency but slightly shortens the filament's
life expectancy.
(C) region of almost perfect vacuum, which significantly
increases the filament's life expectancy but slightly reduces the bulb's
energy efficiency.
(D) volume of chemically inert gas, which significantly
increases the filament's life expectancy but slightly reduces the bulb's
energy efficiency.
Answer: (D) volume of chemically inert gas, which significantly
increases the filament's life expectancy but slightly reduces the bulb's
energy efficiency.
Why: The gas is present to slow sublimation, which would
otherwise lead to a speedy filament failure. This gas is included even though
it costs energy efficiency.
Problem 26:
Some satellites orbit the earth at such large distances
that they are never in the earth's shadow. These satellites are constantly
exposed to full sunlight. With no air around them to take away heat, why don't
these satellites continue to grow hotter forever?
(A) They use air conditioners (which NASA calls
"thermal stabilization units") to eliminate the excess thermal
energy as rapidly as it arrives.
(B) They have solar panels that convert the sun's thermal
radiation completely into electricity and avoid any need to eliminate heat.
(C) Because they are isolated from the sun by empty space,
the sun's heat can't reach them and they don't experience any changes in
temperature.
(D) Their temperatures rise until they are able to
radiate heat away into space as fast as it arrives from the sun.
Answer: (D) Their temperatures rise until they are
able to radiate heat away into space as fast as it arrives from the sun.
Why: Once it gets hot enough, a satellite will radiate
away thermal energy as fast as it arrives.
Problem 27:
Two equal-sized cars are driving side-by-side down the road.
The blue car is a sleek aerodynamic marvel and leaves only a tiny turbulent
wake behind it as it moves. The red car is a boxy aerodynamic catastrophe
that scrambles the air furiously and leaves a huge swirling wake behind it.
As it moves forward, the red car does
(A) the same amount of work on the air it encounters
as the blue car does, but transfers more forward momentum to that air than
the blue car does.
(B) the same amount of work on the air it encounters
as the blue car does, but transfers more energy to that air than the blue
car does.
(C) more work on the air it encounters than the blue
car does, but transfers the same amount of forward momentum to that air
as the blue car does.
(D) more work on the air it encounters than the blue
car does and transfers more forward momentum to that air than the blue car
does.
Answer: (D) more work on the air it encounters than
the blue car does and transfers more forward momentum to that air than the
blue car does.
Why: The boxy car encounters a great slowing drag force
and does more work against it (force times distance) and gives it more momentum
(forces times time).
Problem 28:
It's a hot summer day and your apartment doesn't have air
conditioning. Your roommate decides to cool the room by opening the refrigerator
door. A minute passes and then the refrigerator's compressor starts to whirr
into action. It continues whirring continuously after that. As a result of
opening the refrigerator door, the temperature of the room air
(A) first deceases for about a minute and then begins
to rise steadily thereafter.
(B) decreases steadily from the moment the door opens.
(C) remains constant despite the fact that the door is
open.
(D) drops quickly at first and then decreases steadily
at a smaller rate thereafter.
Answer: (A) first deceases for about a minute and then
begins to rise steadily thereafter.
Why: The chilled contents of the refrigerate briefly cool
the room, but then the electric power consumed by the refrigerator begins
to heat the room by becoming thermal energy in that room.
Problem 29:
Independent, gaseous water molecules can leave the surface
of hot water at 212 °F (100 °C)
(A) and the surface of room temperature water at
68 °F (20 °C) but not the surface of ice at 0 °F (-18 °C).
(B) and the surfaces of room temperature water at 68
°F (20 °C) and ice at 0° F (-18 °C).
(C) but not the surfaces of room temperature water at
68 °F (20 °C) or ice at 0° F (-18 °C).
(D) and the surface of ice at 0 °F (-18 °C) but not
the surface of room temperature water at 68 °F (20 °C).
Answer: (B) and the surfaces of room temperature water
at 68 °F (20 °C) and ice at 0° F (-18 °C).
Why: Colder temperatures only slow the leaving rate of
water molecules, but don't stop that leaving altogether. It simply becomes
rarer.
Problem 30:
A baseball that is hit well by a bat travels at speeds in
excess of 100 mph (160 kilometers per hour) and the boundary layer of air
close to its surface is turbulent. Because of this turbulent boundary layer,
extra energy flows into the air near the ball's surface and this surface layer
has less trouble working its way from the sides of the ball toward the back
of the ball. The ball flies better as a result. The reason why the boundary
level's flow from the ball's sides to its back is difficult is that
(A) the pressure is rising during this passage (from
the sides toward the back) and the air in the flow is actually speeding
up.
(B) the pressure is rising during this passage (from
the sides toward the back) and the air in the flow is actually slowing down.
(C) the pressure is falling during this passage (from
the sides toward the back) and the air in the flow is actually slowing down.
(D) the pressure is falling during this passage (from
the sides toward the back) and the air in the flow is actually speeding
up.
Answer: (B) the pressure is rising during this passage
(from the sides toward the back) and the air in the flow is actually slowing
down.
Why: The air is bending outward to leave the ball and
the pressure in front of it is higher than behind it. The air slows down.
Problem 31:
You are enjoying an elegant candlelit dinner for two but
the waiter has been a little careless with the ice. Your glass of ice water
contains 25% water and 75% ice, while your friend's glass contains 75% water
and 25% ice. The temperature of your glass of ice water
(A) is higher than that of your friend.
(B) is lower than that of your friend.
(C) is the same as that of your friend.
(D) depends on when it was filled. The glass that
was filled first will now be warmer than the glass that was filled second.
Answer: (C) is the same as that of your friend.
Why: Ice and water can only coexist in thermal equilibrium
at one temperature: the freezing temperature.
Problem 32:
As a prank, you fill a friend's saxophone with helium gas.
When she plays the instrument a few seconds later, its pitch
(A) the same as normal, but its volume is abnormally
soft.
(B) is higher than normal.
(C) is lower than normal.
(D) the same as normal, but its volume is abnormally
loud.
Answer: (B) is higher than normal.
Why: Helium is much less dense than air, so it accelerates
and vibrates faster in the same environment.
Problem 33:
If you add salt to an insulated container of ice water (a
roughly equal mixture of ice and liquid water), the temperature of the mixture
will
(A) decrease and some liquid water will convert
into ice.
(B) decrease and some ice will convert into liquid water.
(C) increase and some ice will convert into liquid water.
(D) increase and some liquid water will convert into
ice.
Answer: (B) decrease and some ice will convert into
liquid water.
Why: The dissolved salt stabilizes liquid water relative
to solid ice, so the water fraction increases. This melting requires energy,
so the mixture cools.
Problem 34:
An airplane maintains level flight while consuming the least
amount of fuel when its wings
(A) separate the airstreams evenly and symmetrically
so that both the upper and lower airstreams experience equal changes in
speed and pressure and thus satisfy Bernoulli's equation.
(B) change the horizontal momentum of the airstream as
much as possible.
(C) allow the airstreams to pass by essentially undeflected
and without significant turbulence.
(D) deflect the passing airstream downward without
introducing any significant turbulence into that airstream.
Answer: (D) deflect the passing airstream downward
without introducing any significant turbulence into that airstream.
Why: The lift force comes from deflecting air downward.
The energy transferred to this air is minimized by avoiding turbulence.
Problem 35:
The higher you stand up in a canoe, the higher the overall
center of gravity rises. Eventually, the canoe becomes unstable and tips over
at the slightest disturbance. That instability develops as soon as
(A) the overall center of gravity no longer rises
during a tip and instead descends during a tip.
(B) the buoyant force exceeds your weight.
(C) the canoe's gravitational potential energy exceeds
its kinetic energy.
(D) the net force on the canoe stops rising and instead
begins to decrease.
Answer: (A) the overall center of gravity no longer
rises during a tip and instead descends during a tip.
Why: The equilibrium is stable as long as a tip raises
the canoe's total potential energy and forces arise that accelerate the
canoe back toward the equilibrium. If the total potential energy drops during
a tip, the equilibrium becomes unstable and the canoe is hard to keep upright.
Problem 36:
You are riding a skateboard down a gradual incline. In order
to waste as little energy as possible while still maintaining control over
your direction of motion, the contact between the sidewalk and the wheels
should experience
(A) no friction.
(B) only sliding friction.
(C) only static friction.
(D) both static and sliding friction.
Answer: (C) only static friction.
Why: Static friction is essential to traction and control,
but wastes no energy as thermal energy.
Problem 37:
The giant waves or tsunamis created by earthquakes have
extremely long wavelengths. They travel
(A) extremely slowly and involve water to great
depth in the ocean.
(B) extremely quickly because they involve only the water
near the ocean's surface.
(C) extremely quickly and involve water to great depth
in the ocean.
(D) extremely slowly because they involve only the
water near the ocean's surface.
Answer: (C) extremely quickly and involve water to
great depth in the ocean.
Why: The longer the wavelength of a water surface wave,
the faster that wave travels. And surface waves on water involve water to
a depth about equal to half their wavelengths.
Problem 38:
You wander into the kitchen on a dark, moonless night and
open the refrigerator door. Sadly, the light bulb in the refrigerator has
burned out and the kitchen remains pitch black. Just as you are about to reach
for the carton of chocolate milk, your pet squirrel leaps onto your back and
you twirl around several times before the squirrel heads off for some other
part of the house. You have no idea which way you are facing. Fortunately,
the refrigerator door is still open and you can feel the cold on your face
as you turn in its direction. The physics explanation for this feeling of
cold that you get when you face the refrigerator is that
(A) you are radiating far more heat toward the cold
contents of the refrigerator than they are radiating toward you.
(B) the cold contents of the refrigerator radiate coldness
toward your skin and lower your skin's temperature.
(C) heat is flowing from the rest of the kitchen into
the refrigerator and the pressure of this heat flow causes coldness to accumulate
on the side of your body that's facing the refrigerator.
(D) the cold contents of the refrigerator do a much
better job of absorbing your thermal radiation than do the warmer contents
of the rest of the kitchen.
Answer: (A) you are radiating far more heat toward
the cold contents of the refrigerator than they are radiating toward you.
Why: When you exchange thermal radiation with a cold object,
you lose more heat to it than it loses to you.
Problem 39:
Your friend's enormous new house has bathrooms with showers
on all four floors, including the basement. The spray from the shower in the
basement is significantly harder and faster than the spray from the third-floor
shower. This difference is explained by the fact that water leaving the third-floor
shower has
(A) less of its total energy in the form of gravitational
potential energy and more in the form of kinetic energy.
(B) less total energy and can't produce as much kinetic
energy.
(C) more of its total energy in the form of gravitational
potential energy and less in the form of kinetic energy.
(D) more total energy but its weight slows it down
and prevents it from spraying hard.
Answer: (C) more of its total energy in the form of
gravitational potential energy and less in the form of kinetic energy.
Why: Energy is conserved, so the higher water has more
of its total energy is tied up in the form of gravitational potential and
less is available for kinetic energy.
Problem 40:
The spacecraft used in most science fiction movies never
seem to require refueling. Presumably, they have great energy reserves located
on-board somewhere. But rockets can't operate on energy alone because
(A) they propel themselves forward by pushing stored
mass backward as exhaust.
(B) rockets are heat engines and they need both a hot
source of energy and cold region into which they can deposit that energy.
(C) energy itself has momentum in the downward direction
and cannot contribute to a rocket's upward motion.
(D) energy doesn't weigh anything and rockets need
weight to propel themselves forward.
Answer: (A) they propel themselves forward by pushing
stored mass backward as exhaust.
Why: Rockets need both energy and mass as "fuel."
The mass is thrown backward with the help of the energy.
Problem 41:
You are swimming at the beach. You swim out past the breaking
surf so that you can float among the waves. Each time a wave crest passes,
you travel
(A) vertically -- directly up and then directly
down.
(B) horizontally toward shore for a distance that's proportional
to the slope of the wave crest.
(C) in a circle-up, toward shore, down, and away from
shore.
(D) horizontally toward shore for a distance equal
to one wavelength of the passing wave.
Answer: (C) in a circle-up, toward shore, down, and
away from shore.
Why: A passing wave causes a circular motion of the local
water. That water rises, travels forward in the direction of the wave, descends,
and travels backward away from the direction of the wave before beginning
this cycle again.
Problem 42:
You're flying a kite on a long kite string. You pluck that
string and a wave travels up the string toward the kite. A few minutes later,
the wind is blowing much harder and the string is tauter. You again pluck
the string and another wave forms. This wave travels
(A) at the same speed as the first wave, even if
the string is wet.
(B) slower than the first wave.
(C) at the same speed as the first wave, unless the string
is wet.
(D) faster than the first wave.
Answer: (D) faster than the first wave.
Why: The tauter string involves greater forces and acceleration,
so everything happens and moves faster.
Problem 43:
You have an inclined plane and two balls that are identical
in every respect EXCEPT that one ball (ball A) is frictionless while the other
(ball B) experiences significant friction. You release both balls from the
top of the inclined plane at exactly the same time. Ball A slides down the
plane and ball B rolls down the plane. Which statement is FALSE:
(A) Ball A has more total kinetic energy when it
gets to the bottom of the plane than does ball B when it gets to the bottom
of the plane.
(B) Ball A has more linear momentum when it gets to the
bottom of the plane than does ball B when it gets to the bottom of the plane.
(C) Ball A gets to the bottom of the plane before ball
B.
(D) Ball A has a higher speed when it gets to the
bottom of the plane than does ball B when it gets to the bottom of the plane.
Answer: (A) Ball A has more total kinetic energy when
it gets to the bottom of the plane than does ball B when it gets to the
bottom of the plane.
Why: Both balls have the same amount of total kinetic
energy when they reach the bottom. However, the rolling ball has some of
that kinetic energy in the form of rotational kinetic energy while the sliding
ball has all of its kinetic energy in translational kinetic form.
Problem 44:
A heat engine produces useful work as it transfers heat
from a hot region to a cold region. If the cold region's temperature increases
and the hot region's temperature stays constant, the heat engine will
(A) need to transfer more heat to produce the same
amount of useful work as before.
(B) become more efficient than before at converting heat
into useful work.
(C) have the same efficiency as before at converting
heat into useful work.
(D) be able to produce more useful work while transferring
the same amount of heat as before.
Answer: (A) need to transfer more heat to produce the
same amount of useful work as before.
Why: Heat engines are most efficient when they let heat
flow from very hot to very cold. The closer those two temperatures become,
the smaller the fraction of heat that can be diverted and turned into work.
Problem 45:
Which of the following is not a harmonic oscillator?
(A) a superball bouncing on a ceramic tile floor.
(B) a person bouncing gently up and down at the end of
a bungee cord, near the end of the ride.
(C) a vertical flagpole swaying back and forth.
(D) a tuning fork with its two tines vibrating rhythmically
in opposite directions.
Answer: (A) a superball bouncing on a ceramic tile
floor.
Why: While it is in the air, the superball experiences
a constant downward force (its weight). Since a harmonic oscillator requires
a restoring force that is proportional to displacement from equilibrium,
the bouncing ball isn't a harmonic oscillator.
Problem 46:
A sealed propane cylinder contains both liquid and gaseous
propane (and no air). You put the cylinder outside on a hot day and its temperature
increases. As a result of this rise in temperature, the fraction of propane
molecules that are in gaseous form
(A) increases, but the pressure in the cylinder
remains constant.
(B) and the pressure remain constant, but the thermal
energy in the cylinder increases.
(C) increases and so does the pressure in the cylinder.
(D) remains constant, but the pressure in the cylinder
increases.
Answer: (C) increases and so does the pressure in the
cylinder.
Why: Increasing the temperature shifts the balance between
propane molecules landing on the liquid and leaving the liquid. More leave
than before, so the density of propane molecules in the gas increases. With
an increase in both temperature and density, the pressure of the propane
rises.
Problem 47:
A candle won't burn properly onboard the orbiting Space
Shuttle because, in the freely falling Shuttle, there are no pressure gradients
and no buoyant forces. Without buoyant forces,
(A) there is such strong convection that the flame
actually blows itself out.
(B) the candle's flame falls onto the top surface of
the candle wax and goes out.
(C) the candle's flame floats away from the wick and
the candle spontaneously goes out.
(D) there is no natural convection in the flame to
remove burned gases and bring in fresh oxygen.
Answer: (D) there is no natural convection in the flame
to remove burned gases and bring in fresh oxygen.
Why: Convection is essential to the normal candle flame.
In the absence of gravity, the buoyant force vanishes and so does natural
convection.
Problem 48:
You see a television advertisement for a product that can
be inserted into a light fixture to reduce the incandescent bulb's power consumption.
With this device installed, a 100-watt bulb's filament receives only 50-watts
of power on average. As a result, the bulb will cost less to operate, however
it will produce
(A) somewhat more than half its normal illumination
and the light it emits will be redder than normal.
(B) somewhat less than half its normal illumination and
the light it emits will be redder than normal.
(C) half its normal illumination and the light it emits
will be redder than normal.
(D) half its normal illumination and the light it
emits will be bluer than normal.
Answer: (B) somewhat less than half its normal illumination
and the light it emits will be redder than normal.
Why: The under-heated filament will operate below its
design temperature and will emit more of its thermal radiation as invisible
infrared light.
Problem 49:
An astronaut is orbiting the earth in a circular path at
an altitude of about 187 miles (300 kilometers). Just before takeoff, her
weight was measured to be 140 pounds. As she orbits, her weight is
(A) zero, her velocity is horizontal, and her acceleration
is horizontal.
(B) slightly less than 140 pounds, her velocity is horizontal,
and her acceleration is downward.
(C) much less than 140 pounds, her velocity is zero,
and her acceleration is downward.
(D) zero, her velocity is zero, and her acceleration
is zero.
Answer: (B) slightly less than 140 pounds, her velocity
is horizontal, and her acceleration is downward.
Why: Her distance from the earth's center has barely changed,
so her weight is almost normal. She orbits because, although she accelerates
straight downward (as always), she is moving horizontally so fast that she
misses the earth and falls around it.
Problem 50:
You are delivering pizza to pay your overdue library book
fines. Unfortunately, a poorly timed order for 3 double-cheese and anchovies
pizzas has trapped you aboard the Space Shuttle during liftoff. Everyone on
board is so kind that they agree to let you have a slice yourself once you
are all in orbit. However, they require that you figure out which box contains
the remaining pizza without opening any of the boxes. You place one box after
the next on a scale to weigh it, but each time the scale reads zero. To solve
the puzzle and find the pizza, you
(A) you drop each box from a set height in the cabin
and open the box that hits the cabin floor in the shortest amount of time.
(B) push each box against the scale with your hands and
open the box that reads the highest weight on the scale.
(C) shake each box and open the box that is hardest to
shake.
(D) you release each box from the front of the cabin
and open the box that hits the rear of the cabin in the shortest amount
of time.
Answer: (C) shake each box and open the box that is
hardest to shake.
Why: Weight may be hard to determine in a falling space
shuttle, but you can find mass by shaking an object. Massive objects are
hard to shake.
