Ignore air resistance

Use acceleration due to gravity as 10 m/s2.

1. While standing on a level field a ball is thrown straight upwards. If the ball is to remain in the air for a total time of 10 seconds, what must be the INITIAL SPEED of the ball?

A. 50 m/s B. 60 m/s C. 80 m/s

D. 100 m/s E. 110 m/s

2. A ball is dropped from the top of a building 20 m high. At the same instant, a second ball is thrown upward from the ground at a speed of 20 m/s.

At approximately what height above the ground do the two balls collide?

A. Zero (ground level) B. 5 m C. 10 m

D. 15 m E. 20 m

1. A 2. D