If the speed of a car becomes four times then the kinetic energy becomes

Concept:

Kinetic Energy (K): 

The energy of the body in motion by virtue of motion is called kinetic energy.

\(K = \frac{1}{2}mv^2\)

m is the mass of the body, v is the speed of the body.

Calculation:

Let initial speed is v, and Kinetic energy is K

Then

\(K = \frac{1}{2}mv^2\) -- (1)

Now, the speed is four times.

New speed v' = 4 v

the Kinetic energy will become 

\(K' = \frac{1}{2}mv'^2 = \frac{1}{2}m(4v)^2 =16\times \frac{1}{2}m(v)^2\)

\(\implies K' = 16 \times \frac{1}{2}m(v)^2 \) -- (2)

Putting (1) in (2)

K' = 16 K

So the kinetic energy becomes 16 times.