Question

A fixed pulley is driven by a 100kg mass falling at a rate of 8m in 4s. It lifts a load of 75kgf. Calculate: a).the poweininput to the pulley taking the force of gravity on 1kg as 10N. b).the efficiency of the pulley and the height to which the load is raised in 4s.

Answer 1

The answer and solution is shown below :-)

Answer 2

Answer:

The power and efficiency will be 2000 w and 0.75

Explanation:

Given that,

Mass m = 100 kg

Distance d = 8 m

Time t = 4 sec

Load F= 75 kgf

The effort is 10 N for 1 kg.

So, The effort will be for 100 kg = 1000 N

Load will also be 750 kg.

(a).

The power(P) will be

$P= \dfrac{Effort\times Displacement}{time}$

$P=\dfrac{1000\times8}{4}$

$P=2000\ watt$

(b).

The efficiency will be

$Efficiency =\dfrac{load\times distance}{effort\times distance}$

$E=\dfrac{75\times 8}{1000\times 8}$

$E = 0.75$

Hence, The power and efficiency will be 2000 w and 0.75.