Question

A boy tosses a football upward. If the football rises a vertical distance of 7.2 m and the boy catches it at the same point he released it, what is the velocity of the ball just before he catches it?

Answer 1

Gravitational acceleration = g = -9.81 m/s² (Negative as it is directed downwards)

Vertical distance the football rises to = H = 7.2 m

Velocity of the football at maximum height = V₁ = 0 m/s

Velocity of the football just before the boy catches it = V₂

Time taken by the football to reach the boy's hands from the maximum height = T

When the boy catches the football the displacement of the football is downwards therefore the vertical displacement of the ball is negative.

T = 1.212 sec

V₂ = V₁ + gT

V₂ = 0 + (-9.81)(1.212)

V₂ = -11.9 m/s

Velocity of the football just before he boy catches it = -11.9 m/s