Question

The Kinetic Energy of a body is 400 J. What is its new kinetic energy when the velocity becomes 3 times and mass remains constant ?​

Answer 1

Answer:-

3600 J

Explanation:-

Let the mass of the body be 'm' and velocity of the body be 'v'.

We know that:-

=> K.E. = 1/2mv²

Where:-

• K.E. is kinetic energy of the body

• m is mass of the body.

• v is velocity of the body.

=> 400 = 1/2mv²

=> 400 = 0.5mv². ----(1)

Now, as per given condition, velocity becomes 3 times i.e. 3v and mass remains constant. Hence, the equation for new kinetic energy [K.E'] :-

=> K.E.' = 1/2×m×(3v)²

=> K.E.' = 9/2mv²

=> K.E.' = 4.5mv² ----(2)

On dividing eq.2 by eq.1, we get :-

=> K.E.'/400 = 4.5mv²/0.5mv²

=> K.E'/400 = 9

=> K.E.' = 400×9

=> K.E.' = 3600 J

Thus, new kinetic energy of the body

is 3600J.