Question

A body of mass 2 kg is moving with a momentum of 10 kg m/s.The force needed to increase its kinetic energy by four times in 10 seconds is?

Answer 1

Answer:

the above answer is already right.

Answer 2

The force needed to increase its kinetic energy by four times in 10 seconds is 1 N.

Given,

The mass of the body = 2 kg

Initial momentum = 10 kg m/s

To Find,

The force required to increase its kinetic energy to four times in 10 seconds.

Solution,

It is given that

Momentum initially = 10 Kg m/s.

So, initial velocity = u = 10/2 = 5 m/s.

Also, initial Kinetic Energy = ½mu² = 25 J.

Final Kinetic Energy = (4x25) = 100 J.

So,

½mv² = 100.

v² = (100x2)/2.

v = √100 = 10 m/s.

Now, we use, v = u + at.

So,

10 = 5 + a(10).

a = 5/10 = 1/2 m/s² = 0.5 m/s².

Force needed = ma = (2x0.5)

Force needed = 1 N

Hence, the force needed to increase its kinetic energy by four times in 10 seconds is 1 N.

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