### A man uses a rope to haul a box of weight600N up an inclined wooden...

A man uses a rope to haul a box of weight600N up an inclined wooden plank of effective length 3.0m and on platform 1.0m high. If in doing so, he exerts a force of 400N on the rope.Calculate:
(I) the frictional force between the case and the plank
(ii) the velocity ratio of the machine
(iii) the mechanical advantage
(iv) the useful work done in joules?

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#### Answers (1)

Dende
1 month ago
triangle 1, up
3 hypotenuse, along plank
sqrt (8) = 2 sqrt 2, horizontal

plankward component of weight = 600 [ (2/3) sqrt 2] = 566 N
slopeward component of weight = 600 (1/3) = 200 N
(1) but we pulled with 400 N so friction force = 400-200 = 200 N
(2) velocity up/ velocity along slope = 1/3
(3) pulls with 400 and lifts 600 so 6/4 = 3/2
(4) 600 N * 1 meter up = 600 Joules
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