A wooden block lying on a smooth horizontal surface is simultaneously subjected to…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A wooden block lying on a smooth horizontal surface is simultaneously subjected to four horizontal forces: 15N to the right, 9N to the left, 6N to the right and an unknown force Fu to the left. The block is initially at rest.
(a) Choose the rightward direction as positive and write the expression for the net horizontal force acting on the block in terms of Fu.
(b) The block is observed to remain at rest. Using the result of part (a), determine the magnitude of Fu.
(c) Later the unknown force increases by 3N while the other three forces remain unchanged. Calculate the new net horizontal force on the block and state its direction.