A machine is used to lift a load of 20 N through a height of 10 m. if the efficiency of the machine is 40%, how much work is done?
-
A.
80 J -
B.
500 J -
C.
300 J -
D.
120 J
Correct Answer: Option B
Explanation
Efficiency = ( frac{text{work output}}{text{work input}} times frac{100}{1} )
= 40 = ( frac{20 times 10 }{x} times frac{100}{1} )
= 500J