PHYSICS · Multi-part · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
Three identical sleds are pulled along a level, frictionless snowfield at the same constant speed v=2.0ms−1.
• Sled A is pulled by a rope that is parallel to the direction of motion with a tension of 60N.
• Sled B is pulled by a rope that makes an angle of 30∘ above the direction of motion with the same tension of 60N.
• Sled C is pulled by a rope that makes an angle of 60∘ above the direction of motion with the same tension of 60N.
Assume each rope acts in a vertical plane that contains the line of motion and that the only horizontal force on each sled is the rope tension described above.
(a) Rank, from greatest to least, the magnitudes of the instantaneous rates at which the ropes transfer energy to sleds A, B, and C while the speed is 2.0ms−1. Explain your reasoning clearly.
(b) Sled A suddenly doubles its speed while the tension and direction of its rope remain unchanged. Determine the numerical factor by which the instantaneous rate of energy transfer for sled A changes, and justify your answer.
(c) The person pulling sled B now wishes to match the instantaneous rate of energy transfer that sled A had in part (a) *before* its speed changed. Keeping the angle of 30∘ fixed, calculate the new tension that must be exerted on sled B’s rope to achieve this goal. Show all steps in your calculation.