Question

A missile has been fired with an initial speed $u$. If the speed is tripled, what will be the corresponding change in its kinetic energy?

• A. Remains same
• B. Decreases thrice
• C. Increases nine times
• D. Increases thrice

Answer 1

The correct option is C

Increases nine times

The mathematical expression for Kinetic Energy of an object is $K.E.=\frac{1}{2}m{v}^2$, where m is the mass of the object, v is the speed of the object.

Here, kinetic energy is directly proportional to the square of the speed.

Let initial speed be $v_1$

Initial kinetic energy, $K.E_1=\frac{1}{2}m{v_1}^2$

Let Final speed be $v_2=3v_1$

so, final kinetic energy $K.E_2=\frac{1}{2}m{v_2}^2$