Question

Two balls A and B of mass 2kg are launched through the air from the same height (3m) and at same speed (4 m/s).

If the ball A is launched straight upwards, and the ball B is launched horizontally, what is the ratio of their final velocities when they hit the ground?

Your answer should complete the statement:"Ball A's final velocity is ____ times Ball B's final velocity."

Answer 1

A 2000kg car accelerates from rest to 36 m/s in 6 seconds. What must the power output of the engine be in order to accomplish this? Express your answer in kilowatts, to three significant figures.

Answer 2

Ball A: V^2 = Vo^2 + 2g*h = 0
4^2 + (-19.6)h = 0
h = 0.82 m.
ho + h = 3 + 0.82 = 3.82 m. above gnd.
V^2 = Vo^2 + 2g*h = 0 + 19.6*3.82 = 74.9
V = 8.7 m/s.

Ball B: h = 0.5g*T^2 = 3
4.9T^2 = 3
T = 0.78 s. to hit gnd.
V = Vo + gT = 0 + 9.8* 0.78 = 7.64 m/s.

Va/Vb = 8.7/7.64 =