Question

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

Answer 1

Question#20302

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

Solution:

Let:

$$m = 75 \text{ kg}$$ $$H = 3 \text{ m}$$ $$S = 12 \text{ m}$$ $$F = 250 \text{ N}$$

η−?

According to the law of conservation energy:

$$\frac{\text{mg}}{\eta F} = \frac{S}{H}$$ $$\eta = \frac{\text{mgH}}{SF}$$ $$\eta = \frac{75 \div 9.8 \div 3}{12 \div 250} = 0.735 = 73.5\%$$

Answer: 73.5%