Question

Certain force acting on a 20 kg mass changes its velocity from
5 ms- to 2 m s-l. Calculate the work done by the force.
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Answer 1

Answer:

Explanation:

Known Terms:-

u = Initial speed

v = Final speed

m = Mass

w = Work done.

Given:-

Mass of the body, m = 20 kg

Initial velocity attain by the object, u = 5 m/s

Final velocity attain by the object, v = 2 m/s

To Calculate:-

Work done by the force.

Formula to be used:-

and  

Change in kinetic energy that is Final kinetic energy - Initial kinetic energy

Solution:-

Putting all the values:-

Initial kinetic energy of the body:-

=  

=  

= 250 joule

Final kinetic energy of the body:-

=  

=  

= 40 joule

Work done by the force :-

Change in kinetic energy

= Final kinetic energy - Initial kinetic energy

= (40 - 250) joule

= -210 joule

Hence, the work done by the force is -210 joule.