Question

5. A man carrying a bag of mass 25 kg climbs up to a height of 10 m in 50 seconds. Calculate the power delivered
by him to the bag. (Take g = 9.8 m/s2)
​

Answer 1

Solution :-

Given ,

• Mass of bag = 25kg
• Height = 10m
• Time taken to climb = 50s
• Acceleration due to gravity = 9.8m/s²

We need to find ,

• Power delivered by him to the bag = ?

Now , as we know that

• Power = Work/time

Substituting , work = mgh & time = t

• Power = mgh/t

Now substituting the known values ,

→ Power = 25 × 10 × 9.8/50

→ Power = 98/2

→ Power = 49 W

Note :- Make sure that all units should be in S.I. units .

Hence , power = 49W .

Answer 2

Explanation:

Given:-

Mass of bag=m=25kg

Height =h=10m

Time taken =50s

Acceleration due to gravity =g=9.8m/s $^2$

To find:-

Power delivered by the man

Solution:-

As we know that

$\boxed {\sf Power=\dfrac {Work}{Time}}$

$\boxed {\sf Work=mgh}$

$\boxed {\sf \longrightarrow Power=\dfrac {mgh}{t}}$

• Substitute the values

$\\\qquad\qquad\displaystyle\sf {:}\rightarrowtail Power=\dfrac {\cancel {25}\times 9.8\times 10}{\cancel {50}}$

$\\\qquad\qquad\displaystyle\sf {:}\rightarrowtail Power=\dfrac {98}{2}$

$\\\qquad\qquad\displaystyle\sf {:}\rightarrowtail Power=49W$

$\\\\\therefore\sf Power\:delivered\:by\:the\:man\;is\:49\: Watts.$