Find the percentage of the total work lost to friction if 22.9 J of work is put into pushing a block up a ramp resulting in 13.5 J of stored potential energy at the top. Report the percentage lost as a positive number.

41.0%

Explanation:

According to the law of conservation of energy, in absence of friction the work done on the block must be equal to the final potential energy stored on the block at the top of the ramp.

However, here there is friction acting opposite to the motion of the block, so part of the energy is lost due to the work done by friction. The energy lost is:

where:

W = 22.9 J is the work done by the applied force

E' = 13.5 J is the potential energy stored at the top of the ramp

Therefore,

And therefore, the percentage loss of energy is:

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