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# What is the answer to this Kinectic Energy question ? watch

1. A 100000kg train has a kinetic energy of 28000000J how fast is the train going?

2. Use the formula energy transferred = 1/2 x mass x velocity squared and rearrange
3. Kinetic Energy = 0.5 * mass * velocity2
1/2mv2 = 28000000J

1/2*100000*v2 = 28000000J

4. (Original post by Wildnatxox)
A 100000kg train has a kinetic energy of 28000000J how fast is the train going?

The answer would be 23.7 (1dp)
Why?
Well the formula for kinetic energy is:0.5 ×mass× velocity squared

So to find the velocity you just rearrange the formula so it would be:

The square root of 2× kinetic energy divided by the mass. In yout case it would be square root of 2 × 28000000 ÷100000.
Hope it wasnt too confusing!

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