PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A 50kg sled rests on horizontal snow. Starting at t=0, a person pulls the sled to the right with a constant horizontal force of 250N. The coefficient of kinetic friction between the sled and the snow is μk=0.10. Take g=9.8ms−2.
(a) Determine the magnitude of the net horizontal force acting on the sled.
(b) Derive an expression for the sled’s speed v(t) as a function of time while the force is applied.
(c) Using your result from part (b), obtain an explicit expression for the instantaneous power P(t) delivered by the pulling force.
(d) Calculate the time at which the instantaneous power first reaches 500W.
(e) Describe the qualitative shape of the power-versus-time graph for this situation and explain how the presence of kinetic friction alters the graph compared with an ideal frictionless case.