A wooden block of mass is pushed up a smooth inclined plank that makes an angle of…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A wooden block of mass 4kg is pushed up a smooth inclined plank that makes an angle of 30∘ with the horizontal. A constant force of 200N, applied parallel to the surface of the plank, moves the block a distance of 5m along the plank from point X at the bottom to point Y at the top. The block is then allowed to slide back down the same smooth plank without any push and comes to rest again at point X.
Answer the following questions.
(i) Calculate the vertical height gained by the block when it reaches point Y.
(ii) Determine the mechanical work done by the applied 200N force on the block during its upward motion from X to Y.
(iii) What is the work done by the same applied force on the block during its return from Y back to X? Give reasons for your answer.
(iv) Compute the net work done by the applied force on the block for the complete journey X → Y → X, and explain what this reveals about the relation between work and displacement.