After the first snowfall of the year, you decide to go sledding with some friends. You find the perfect hill that slopes downward steeply and then ends at an open field, which is flat and horizontal. The snow is very slippery so you can neglect the effects of friction between the snow and the bottom of the sled. Also ignore air resistance (drag forces) in answering the following questions.
1. As you zip down the steep portion of the hill on your sled, what forces act on you and in what direction do they act? What are the amount and direction of the net force acting on you (for the amount, give a descriptive answer by comparing it to your weight, i.e. more, less, equal, or zero)?
2. After you reach the bottom of the hill and arrive at the open field, how does your velocity change as you slide across the field? Why does your velocity change in this way?
3. After climbing up the steep hill several times you are exhausted. Your friend suggests you take a different route to the top, which is longer, but has a more gradual incline. Compare the total amount of work you do on the sled in carrying it up the steep slope, to carrying it up the gradual incline.
4. During your descent of the steep portion of the hill describe how your gravitational potential energy, kinetic energy, and total energy change.
5. You and a friend decide to have a race to the bottom of the hill. You have identical sleds, but your friend weighs considerably more than you. Which one of you gets to the bottom first?
Bowling is a game in which a heavy ball is rolled down a smooth level surface, called the lane, toward ten pins. The object is to knock down all of the pins. You have two throws on each turn to try knocking the pins down.
6. If you release the bowling ball without putting any spin on it, the ball will initially slide down the lane without rolling. As it continues down the lane it will start to roll. What force causes the ball to start rolling? Describe how this force causes the ball to start rolling (hint: where and in what direction is the force acting).
7. Bowling balls come in different masses. If you use the same force to roll a light ball down the lane as used in rolling a heavy ball, which ball will take longer to hit the pins?
8. It is the second throw of your turn and there is only one pin left standing. You have excellent aim and the ball smacks the pin squarely. After the collision the pin is moving forward, in the same direction the ball was initially moving. The ball continues to move forward, but at a lower speed than it had before the collision. Explain this behavior using either the concept of conservation of energy or conservation of momentum. Neglect friction and air resistance for this part of the problem.