Question

A machine raised a load of 360 N through a distance of 200 mm. The effort, a force of 60 N moved 1.8 m during the process. Calculate effect of friction.

(a) 10 N

(b) 20 N

(c) 30 N

(d) 40 N

I have been asked this question in examination.

My question is based upon Relative Velocity of Two Bodies Moving in Straight Lines topic in section Velocity in Mechanisms of Machine Kinematics

Answer 1

The correct choice is (b) 20 N

To explain I would say: Given, load raised, W = 360 N

Effort applied, P = 60 N

Distance moved by the effort, y = 1.8 m

Distance moved by the load, x = 200 mm = 0.2 m

Mechanical advantage, M.A. = W/P = 360/60 = 6

Velocity ratio, V.R. = y/x = 1.8/0.2 = 9

Effort lost in friction, FP = P – W/V.R. = 60 – 360/9 = 20 N.