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Kinetic Energy Ping Pong ball Question

  • #1
[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=?


Homework Equations



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:

Answers and Replies

  • #2
Doc Al
Mentor
44,862
1,109
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.)
 
  • #3
Thank you Doc Al.

The correct answer was 127m/s
 

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