A student drags a sled along a frozen lake by pulling a rope that is parallel to the…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A student drags a 15kg sled along a frozen lake by pulling a rope that is parallel to the ice surface. The pull is a steady 60N toward the east, while sliding friction on the ice opposes the motion with a force of 15N toward the west.
(i) Draw a clear, labelled free-body diagram of the sled showing all horizontal and vertical forces.
(ii) Calculate the net horizontal force acting on the sled and state whether the forces are balanced or unbalanced.
(iii) Determine the acceleration of the sled.
(iv) If the sled starts from rest, find its speed after 4s of being pulled.
(v) The student’s friend now helps by exerting an additional force of 40N in the same direction. Keeping all other forces unchanged, calculate the new acceleration of the sled.