Block On Incline 2 (w/ work) 1 2 3 4 5 6 7 A mass m 15 kg is pulled along a hori
ID: 1794191 • Letter: B
Question
Block On Incline 2 (w/ work) 1 2 3 4 5 6 7 A mass m 15 kg is pulled along a horizontal floor, with a coefficient of kinetic friction 0.06, for a distance d-8.5 m. Then the mass is continued to be pulled up a frictionless incline that makes an angle = 34° with the horizontal. The entire time the massless rope used to pull the block is pulled parallel to the incline at an angle of 34° (thus on the incline it is parallel to the surface) and has a tension T 44 N. 1) What is the work done by tension before the block gets to the incline? JSubmit Help 2) What is the work done by friction as the block slides on the flat horizontal surface? J Submit Help 3) What is the speed of the block right before it begins to travel up the incline? s Submit HelpExplanation / Answer
1) W = F.d = F d cos(theta)
W = 44 x 8.5 x cos34 = 310 J
2) f= uk m g = 0.06 x 15 x 9.8 = 8.82 N
W = 8.82 x 8.5 x cos180 = - 74.97 J
3) Net work done = change in KE
310 - 74.97 = 15 v^2 /2
v = 5.6 m/s
4) KEi = 15 x 5.6^2 /2 = 235.03 J
m g L sin34 = 235.03
L = 2.86 m
5) Work donme by gravity = - 235.03 J
6) Net work done = 0
{ net work done = change in KE = 0 - 0 = 0 }