Use energy conservation to find the approximate final speed of a basketball dropped from a height of 2 meters (roughly the
height of a professional basketball player). Why don't you need to know the mass of the basketball?
6.X.93 (a) A 0.5 kg teddy bear is nudged off a window sill and falls 2 m to the ground. What is its kinetic energy at the instant it
hits the ground? What is its speed? What assumptions or approximations did you make in this calculation? (b) A 1.0 kg
flowerpot is nudged off a window sill and falls 2 m to the ground. What is its kinetic energy at the instant it hits the
ground? What is its speed? How do the speed and kinetic energy compare to that of the teddy bear in part (a)?
6.X.94 You throw a ball of mass 1.2 kg straight up. You observe that it takes 3.1 s to go up and down, returning to your hand.
Assuming we can neglect air resistance, the time it takes to go up to the top is half the total time, 1.55 s. Note that at the top
the momentum is momentarily zero, as it changes from heading upward to heading downward.
(a) Use the Momentum Principle to determine the speed that the ball had just after it left your hand.
(b) Use the Energy Principle to determine the maximum height above your hand reached by the ball.