A boy throws a ball with an initial velocity of 25 m/s at an angle of 30° above the horizontal. How high above the projection point is the ball after 2.0 s?
A) 5.4 m
B) 13 m
C) 25 m
D) 43 m
E) 50 m

Question

Quizplus · Accepted Answer

The correct answer is A because the ball is at its maximum height after 2.0 s. The vertical component of the initial velocity is 25 m/s * sin(30°) = 12.5 m/s. The acceleration due to gravity is -9.8 m/s^2. The time it takes for the ball to reach its maximum height is 12.5 m/s / 9.8 m/s^2 = 1.28 s. The maximum height is 12.5 m/s * 1.28 s - 0.5 * 9.8 m/s^2 * (1.28 s)^2 = 5.4 m.

A Boy Throws a Ball with an Initial Velocity of 25