physics

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A racing dog is initially running at 20.0 m/s, but is slowing down.
Question: How fast is the dog moving when its kinetic energy has been reduced by half?
Question: By what fraction has its kinetic energy been reduced when its speed has been reduced by half?

  • physics -

    Use the fact that
    kinetic energy = (1/2)MV^2.

    For half the kinetic energy, the V^2 term must be reduced from 400 to 200, in this case.

    That means V = 14.14 m/s

    If you reduce speed by half, you have 1/4 the kinetic energy

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