Question

A truck and a car have same momentum. The kinetic energy of the car is:

• A. more than truck
• B. less than truck
• C. equal to truck
• D. none of the above

Answer 1

The correct option is A

more than truck

Mathematical expression for kinetic energy:

$$\begin{gathered} K.E.=\frac{1}{2}\times m\times v^2 \\ \therefore K.E=\frac{p^2}{2m} \end{gathered}$$ $[\because p=m\times v]$

where,

$$\begin{gathered} K.E.=KineticEnergy \\ m=mass \\ v=velocity \\ p=momentum \end{gathered}$$

1. From the above expression, it is clear that kinetic energy is inversely proportional to mass; momentum remains constant.
2. Since, a truck and car have the same momentum but a car has greater kinetic energy.

Hence, the correct answer is option (A).