Lakhmir Singh Solutions Class 9 Physics Solutions for Exercise in Chapter 4 - Work And Energy

Question 51 Exercise

a) Define the term ‘work’. Write the formula for the work done on a body when a force acts on the body in the direction of its displacement. Give the meaning of each symbol that occurs in the formula.

b) A person of mass 50kg climbs a tower of height 72 meters. Calculate the work done.


a) Work is done when an applied force produces motion in a body.

The formula for work done is:

W = Fs


W is the work done

F is the force applied

s is the distance traveled

b) Mass of the person, m = 50kg

Height of tower, h = 72m

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

Work done, W = mgh = 35280 J

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