PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A horizontal force that varies with time, F(t)=(8.0N/s)t, is applied to a 4.0kg block that is initially at rest on a horizontal tabletop at t=0. The coefficients of friction between the block and the tabletop are μs=0.50 and μk=0.38.
(a) For the time period before the block begins to slide, express the magnitude of the friction force on the block as a function of time.
(b) Determine the time tc at which the block first starts to move.
(c) For t>tc, write an expression for the block’s acceleration as a function of time.
(d) Calculate the speed of the block at t=3.50s. Clearly state all steps in your reasoning.