# kinetic energy and loss of potential energy

1. What velocity does a 1-kg object have when its kinetic energy is 1 J?

2. A man skis down a slope 200 m high. If his velocity at the bottom of the slope is 20 m/s, What percentage of his potential energy was lost due to friction and air resistance?

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#### Solution Preview

1. The kinetic energy is Ek = 0.5mv^2.

Ek = 1 J

m = 1 kg,

Thus

0.5 * 1 * v^2 = 1

v^2 = 2

v =sqrt (2) = 1.4 m/s

The velocity is about 1.4 m/s to have kinetic energy of 1 J for a 1-kg object.

2. When he is at the top of the slope, his kinetic energy is ...

#### Solution Summary

The solutions provides an example of working with loss of potential energy when the man skies down the slope.

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