A trolley is moving southward on a frictionless track at a constant speed of
PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A trolley is moving southward on a frictionless track at a constant speed of 3m/s. Two horizontal forces act on it simultaneously: a 20N force towards the south and a 20N force towards the north.
(i) Determine the net force on the trolley and classify the forces as balanced or unbalanced.
(ii) Explain why the speed of the trolley remains unchanged under the forces in part (i).
(iii) An additional horizontal force of 5N towards the south now begins to act while the previous two forces continue. Find the new net force, state whether the forces are now balanced or unbalanced, and predict qualitatively how the speed of the trolley will change after this instant.