Question

If the speed of the car is doubled, how does its kinetic energy change?

Answer 1

Answer:

The change in the kinetic energy of the object as the speed changes is proportional to the square of the factor by which the speed changes. For example if the speed of the object becomes double, its kinetic energy changes to four times the initial kinetic energy.

Answer 2

The kinetic energy will become four times the previous value.

The expression for the kinetic energy of a body is

Kinetic energy = $\frac{1}{2}$mv², where m is the mass of the body, v is the velocity of the body.

Let u be the initial velocity

Let the new velocity be v

On doubling the velocity, the new velocity will become 2u

So, v = 2u

Kinetic energy after doubling the velocity= $\frac{1}{2}$ mu²

Kinetic energy after doubling the velocity = $\frac{1}{2}$ mv²

                                                                      = $\frac{1}{2}$ m(2u)²

                                                                      =4( $\frac{1}{2}$ mu² )

Kinetic energy after doubling the velocity = 4(Kinetic energy )

Therefore, on doubling the velocity, the kinetic energy becomes 4 times.