4.5 Consider the problem with the wheel to transport boxes in Example 3.6. Since gravity is used to make the boxes move, there is actually one energy transformation involved.

(a) Express the problem in terms of a signal and response, for example with the potential energy as the signal and the kinetic energy as the response.

How can the fact that the force component working in the direction of box motion changes when the wheel rotation be taken into account?

(b) Can there be reasons for not expecting a smooth box acceleration and, in that case, how to deal with such a variation over time, for example in terms of factors?