Physics 20: Linear Kinematics

Question

A baseball is thrown upward with an initial speed of 35.0 m/s. What is its velocity at 2.00 s? (15.4 m/s up)

I want to know how to find the answer

Answer 1

The ball is released at an initial velocity of 35.0m/s, but gravity is acting on it, which means the velocity of the ball will change.

The acceleration of gravity is -9.8m/s^2, which means every second the ball's velocity decreases by 9.8m/s.

This means that after two seconds, the ball's velocity will decrease by 9.8m/s * 2 or 19.6m/s

Therefore, the ball's velocity after 2 seconds is 35m/s - 2 * 9.8m/s = 15.4m/s

Another way you could do this, is plug into the equation:

a = (vf - v0)/t , where a is acceleration, vf is final velocity, v0 is initial velocity and t is time

Answer 2

Gravity changes speed by 10m/s every second ... after 2 sec, ball loses 20 m/s down to 15 m/s :)