A worker in a warehouse pushes two wooden boxes across a floor at a constant speed, as shown in the diagram below.

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j ?

What is the weight of a 8-kg substance in n, kn, kg·m/s2, kgf, lbm·ft/s2, and lbf?

Difference between series and parallel circuits