Question

A baseball is traveling (+20 m/s) and is hit by a bat. It leaves the bat traveling (-30 m/s). What is the change in the velocity? Remember that direction is what makes velocity different than speed.


A. 50 m/s

B. 30 m/s

C. 20 m/s

D. 10 m/s

Answer 1

The answer is A. 50 m/s

I took the test and completed the study guide in class and got it correct.

Answer 2

Answer: A. 50m/s

Explanation

Step 1

The first step is to define velocity.  Velocity is a measure of how fast displacement is changing with time. When discussing the velocity of a object we have to take into account that direction is important.

Step 2

The second step is to calculate the change in velocity.  The object is initially travelling with a velocity of $+20m/s$ and then hits the bat, changes directions and travels at $-30m/s$ in a direction opposite to it's initial direction. The change in velocity is calculated as shown below,

$\Delta v=v_1-v_2\\\Delta v = +20m/s-(-30m/s)=+20m/s +30m/s = 50m/s.$

The correct answer is $50m/s$