A mass m = 13.0 kg is pulled along a horizontal floor, with a coefficient of kin

Question

A mass m = 13.0 kg is pulled along a horizontal floor, with a coefficient of kinetic friction ?k = 0.08, for a distance d = 6.7 m. Then the mass is continued to be pulled up a frictionless incline that makes an angle ? = 38.0? with the horizontal. The entire time the massless rope used to pull the block is pulled parallel to the incline at an angle of ? = 38.0? (thus on the incline it is parallel to the surface) and has a tension T = 45.0 N. **the work done by tension before the block gets to the incline= 237.58N 2) What is the work done by friction as the block slides on the flat horizontal surface? J AND What is the speed of the block right before it begins to travel up the incline? m/s

Explanation / Answer

a). N + Tsin38 = mg thus N = 99.69 N friction force = uN = 7.97 N work done by friction on flat surface = - 7.97 * 6.7 = 53.43 J b). Net force on block in horizontal direction = Tcos38 - Friction force = 27.49 N a = 27.49/13 = 2.11 m/s^2 now use v^2 = u^2 + 2as here u=0; a= 2.11; s = 6.7m thus v = 5.32m/s

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