Question

Suppose that the force required to push a saw back and forth 30 times, moving it forward 12cm and back 12cm each time, how much work do you do?

Answer 1

During the one turn the saw covers the distance $d = 12cm +12 cm = 24cm = 0.24m$ moving under the force, say, $F$ (in Newtons). Then, the work done in one turn is:

$$A_1 = Fd = 0.24F \space [N\cdot m]$$

The total work in 30 turn then is:

$$A = 30A_1 = 30\times 0.24F \space [N\cdot m] = 7.2F \space [N\cdot m]$$

Answer. $7.2F \space [N\cdot m]$.