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## Homework Statement

A block slides to a stop along a table top. Which of the following statements is true?

A. The work done by friction is equal to the force of friction times the distance that the block slid.

B. The work done on the block is equal to the force of friction times the distance that the block slid.

C. The work done on the table is equal to the force of friction times the distance that the block slid.

D. The work done on the block is equal to the sum of its changes in kinetic and internal energies.

## Homework Equations

W = Ffr*d

## The Attempt at a Solution

The answer given by the book is D but I do not understand why A is the incorrect answer. I thought if friction is doing work against the direction of motion of the block it would just equal exactly as what is stated - force of friction direction parallel to motion times the distance? As for D, wouldn't it be equivalent to A since whatever changes in potential and kinetic energy would entail and equivalent change in friction?

I'm really new to physics, so I'm missing very key concepts that I am not able to piece together. So thank you for your help and patience.

-Taminem