Question

61. Two persons A and B each of mass
60 kg are carrying loads 15 kg each. If
they reach the top of a building of height
10 m in 20s and 40s respectively, the ratio
of their efficiencies is
1) 1:1 2) 1:2 3) 2:1 4)4:1​

Answer 1

Answer:

I don't know what is this

Answer 2

The ratio  of their efficiencies is 1 : 1 .

Given :

Two persons A and B each of mass  60 kg are carrying loads 15 kg each .

Height of building , h = 10 m .

Time taken by persons A and B in 20 s and 40 s respectively .

We know , efficiency is the ratio of output to the input power.

For person A ,

$efficiency_A=\dfrac{\dfrac{(M+m)gh}{20}}{\dfrac{mgh}{20}}\\\\\\efficiency_A=\dfrac{20\times75}{20\times 15}\\\\efficiency_A=5$

For person B ,

$efficiency_B=\dfrac{\dfrac{(M+m)gh}{40}}{\dfrac{mgh}{40}}\\\\\\efficiency_B=\dfrac{40\times75}{40\times 15}\\\\efficiency_B=5$

Therefore , $\dfrac{efficiency_A}{efficiency_B}=\dfrac{5}{5}=1$

Therefore , the ratio  of their efficiencies is 1 : 1 .

Learn More :

Efficiency

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