PmWiki | THS / EnergyHWSPring

In class we used the ball rolling off a 1m table at 2 m/s to solve the following problems using conservation of energy techniques (used a table):

a. How fast is the ball falling when it is half the distance to the ground?

b. How high is the ball when the speed is 3 m/s?

1. Although we used 50g for the mass of the ball in these problems, was the mass really needed to solve these problems? Why or why not? The best way to answer this is to look at your algebraic equations PE1 + KE1 = PE2 + KE2 and see what happens to m.

2. Suppose you have a spring inside a vertical tube with a 50 g ball sitting on top of the spring that you intend to shoot straight up into the air. Suppose you pulled down a lever 10 cm and latch it in place (cocked), and suppose the constant of 5 N/m. If you assume height = zero is at the top of the relaxed spring, calculate the following using a "conservation of energy table"...

a. How high does the ball go?

b. At what point does the ball reach its maximum speed? (Logic question)

c. What is the speed of the ball when the spring is in its relaxed position?

3. Does the mass of the ball make a matter for #2? Why or why not? The best way to answer this is to look at your algebraic equations PE1 + KE1 = PE2 + KE2 and see what happens to m.