Question

Certain force acting on a 20 kg mass changes its velocity from 5 m/s to 2 m/ s. Calculate the work done by the force.

Answer 1

Hey!! Here is your Answer!!

Mass of the object, m = 20 kg

Total work done by the force = Change in the kinetic energy of the object

Work Done = 1/2mv1^2 - 1/2mv2^2

= 1/2×20×4 -1/2×20×25

= 40-250

= -210 J

•: Work Done By the Force is -210 J

Hope it helps you!!

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Answer 2

Answer:

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:-

$\frac{1}{2}mv^2$ and $\frac{1}{2}mv^2$

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

Solution:-

Putting all the values:-

Initial kinetic energy of the body:-

= $\frac{1}{2}mv^2$

= $\frac{1}{2}(20)(5)^2$

= 250 joule

Final kinetic energy of the body:-

= $\frac{1}{2}mv^2$

= $\frac{1}{2}(20)(2)^2$

= 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.