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An athlete is running at a constant velocity with a javelin held in his right hand. The force he is applying on the javelin as he carries it is 5.0 newtons. If he covers a distance of 10 meters, what work has he done on the javelin?

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Since the force he is applying is 5N and he carries it a distance of 10 meters and the displacement and the force are assumed to be in the same direction we have
5*10 so 50 J

Answer:

He has done a work of 50 J on the javelin.

Explanation:

The work can be defined as:

\(W = F \cdot d \cos \theta\) (1)

Where W is the work, d is the distance and \(\theta\) is the angle between the force and the direction of the displacement.

For this particular case the force has the same direction of the displacement, so \(\theta = 0^{\circ}\)

Then, replacing all the values in equation 1 it is gotten:

\(W = (5.0 N) \cdot (10 m) \cos 0^{\circ}\)

\(W = 50 N.m\)

\(W = 50 Kg.m/s^{2}.m\)

\(W = 50 Kg.m^{2}/s^{2}\)

But 1J = \(Kg.m^{2}/s^{2}\), therefore:

\(W = 50 J\)

Hence, he has done a work of 50 J on the javelin.

Key term:

1J = 1 Joule