A 20kg mass is to be pulled up a slope inclined at 30^\circ to the horizontal. If efficiency of the plane is 75%. The force required to pull the load up the plane is J [g=10ms\(^{− 2}\)]
A
87N
B
73.5N
C
133.3N
D
533.2N
Verified Correct Answer: C.
Physical Principles & Numerical Solution
V. R = \(\frac{1}{Sin\theta}\)
m = 20kg
V.R = \(\frac{1}{Sin 30}\)
= 2
Efficiency = 75%
Load = mg
= 20 x 10 = 200N
Efficiency = \(\frac{M.A}{V.R} \times 100\)
75/100 = \(\frac{M.A}{2}\)
M .A = \(\frac{75 \times 2}{100}\)
M. A = 1.5
Since M. A. = \(\frac{\text{Load}}{\text{Force}}\)
Force = \(\frac{200}{1.5}\)
= 133.3N
Source: Myschool Past Questions Archive (Record #47684)