Physics question

Question

If a ball is kicked with a perfectly horizontal velocity of 22.0 m/s and the ball was 1.3 m above the ground when it was released, how far will it fly horizontally before it strikes the ground?

a)11.3

b) 16.6

c)14

d) 22.7

Answer 1

With the starting height at 1.3 m, the time of flight will be just over 1/2 second. In that time the ball will be able to travel 11.3 m horizontally before it reaches the ground.

Answer 2

Since the initial vertical velocity is zero, the vertical motion depends only on the height. What's important is the time it takes to hit the ground. The simple form of the vertical motion equation is d = (1/2)at². Solving for time, t = √(2d/a) = √(2·1.3 m / 9.8 m/s²) = 0.515 s

In that time, the ball moves horizontally at a constant rate of 22.0 m/s. For constant velocity, d = v·t

d = (22.0 m/s)·(0.515 s) = 11.3 m (answer a)