Question

Certain force acting on a 20kg mass changes its velocity from 18km/hr to 36km/hr Calculate the work done by force

Answer 1

Hello friend
------------------
------------------

⭐⭐ HERE IS YOUR ANSWER⭐⭐⭐

Whe know that,

Work = Change in kinetic energy

That's why first we have to calculate the kinetic energy in both cases.

First let's write the given,

Given :

Mass = 20kg

Initial velocity = 18km/h

Final velocity = 36km/h

Note : Here the velocity is given in km/h,but we need it in m/s and for that we have to convert them.

We know that,

1km/h = 1000/3600

= 5/18 m/s.

So,in first case the velocity is given as,

18km/h which will be in m/s,

= 18 x 5/18

= 5 m/s.

In second case the velocity is given as,

36km/h which will be in m/s,

= 36 x 5/18

= 10 m/s.

i.) In first case :

Mass = 20kg

Velocity = 5 m/s.

hence,

Kinetic energy = 1/2mv^2

kinetic energy = 1/2 x 20 x (5)^2

kinetic energy = 1/2 x 20 x 25

kinetic energy = 1/2 x 500

kinetic energy = 500/2

kinetic energy = 250 J



ii.) In second case,

Mass = 20kg

Velocity = 10 m/s

hence,

kinetic energy = 1/2 mv^2

K.E = 1/2 x 20 x (10)^2

K.E = 1/2 x 20 x 100

K.E = 1/2 x 2000

K.E = 2000/2

K.E = 1000 J

So now we got the both kinetic energy,

By applying the formula....we get

Work done = Change in kinetic energy

= 1000 - 250

= 750 J

⭐⭐ Therefore, the work done by the force is 750 J ⭐⭐


I hope this will helps you ........


Thanks.