A child pulls a wooden toy cart along a horizontal surface by applying a force of…
PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A child pulls a wooden toy cart along a horizontal surface by applying a force of 100N through a string that makes an angle of 30∘ above the horizontal. The cart moves in a straight line for 20m.
(a) Calculate the work done by the child’s pull on the cart. State the sign of this work.
(b) Determine the work done by the weight of the cart for the same displacement and state its sign.
(c) If the cart is now pulled with the same force along a frictionless horizontal surface for the same distance but the string is held exactly horizontal, what will be the work done by the child? Explain any change in magnitude or sign compared with part (a).