# Kinetic Energy Ping Pong ball Question

islanderman7
[SOLVED] Kinetic Energy Question

## Homework Statement

A 7.0 kg bowling ball moves at 2.35 m/s. How fast must a 2.40 g Ping-Pong ball move so that the two balls have the same kinetic energy?

m1= 7.0kg
v1= 2.35m/s
m2= .0024kg
v2=?

I know that:
KE= 1/2mv^2

## The Attempt at a Solution

I set my equation like so:
KE1=KE2

and I reduced it to this:
m1v1=m2v2

I plugged in the values and solved for v2:
(7.0kg)(2.35m/s)=v2 (.0024kg)
v2= 6854.17

I put this answer in and it tells me...
wrong check mark
Your answer differs from the correct answer by orders of magnitude. m/s

What am I doing wrong? Please point me in the right direction.

Last edited:

Mentor
I know that:
KE= 1/2mv^2
Good.

## The Attempt at a Solution

I set my equation like so:
KE1=KE2
Good.

and I reduced it to this:
m1v1=m2v2
You made an error here. The kinetic energy equation doesn't reduce to this.

(Don't leave off squaring the speeds.)

islanderman7
Thank you Doc Al.

The correct answer was 127m/s