During a physics demonstration, an instructor pushes a low-friction cart along a straight, level track. The instructor wishes to transfer exactly 50J of energy to the cart over a distance of 2.5m by exerting a constant force directed 20∘ below the horizontal.
(a) Determine the magnitude of the constant force the instructor must apply.
(b) The instructor instead chooses to push at the same angle but over only 1.5m. Calculate the amount of energy transferred to the cart in this case and comment on how it compares to the intended 50J. Provide reasoning based on your calculation.