Question 257: Laws of Motion

Question

250 N force is required to raise 75 kg mass from a pulley. If rope is pulled 12 m then the load is lifted to 3 m. the efficiency of pulley system will be

Accepted Answer

Load W = Mg = 75 ÃÂ 10 = 750 N
Effort (P) = 250 N
$$ 	herefore $$ Mechanical advantage
$$ = {{load} \over {effort}} = {W \over P} = {{750} \over {250}} = 3$$
Velocity ratio
$$ = {{distance\,travelled\,by\,effort} \over {distance \,travelled\,by\,load}} = 4$$
Efficiency $$(\eta)  = {{Mechanical\,advantage} \over {Velocity\,ratio}}$$
$$ = \left( {3/4} ight) 	imes 100 = 75\% $$

Answer

25%

Answer

33.3%

Answer

75%

Answer

90%

Laws of Motion

250 N force is required to raise 75 kg mass from a pulley. If rope is pulled 12 m then the load is lifted to 3 m. the efficiency of pulley system will be

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