A refrigerator with a weight of 1,127 newtons needs to be moved into a house using a ramp. The length of the ramp is 2.1 meters, and its height is 0.85 meters. What is the percentage efficiency if a force of 496 newtons is applied to the refrigerator?

A. 44 percent
B. 58 percent
C. 64 percent
D. 76 percent
E. 92 percent

Respuesta :

496/1127 = 0.44 = 44% 

sin A = 0.85/2.1. 
A = 23.9o. 

Fp = 1127 sin23.9 = 457 N. = Force parallel to the ramp. 

Fn = 1127 Cos23.9 = 1,030 N. = Force 
perpendicular to the ramp = Normal force. 

Eff. = Fp/Fap = 457/496 = 0.92 = 92%
Correct answer: 92%
The answer will be D. 76 percent since 496 is out of 1,127N