A 20kg mass is to be pulled up a slope inclined at 30° 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
Correct Answer: C
Explanation
V. R = \(\frac{1}{Sinθ}\)  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
