Question

When the speed of a moving body is doubled

• A. Its acceleration is doubled
• B. Its momentum is doubled
• C. Its kinetic energy is doubled
• D. Its potential energy is doubled

Answer 1

The correct option is B

Its momentum is doubled

Explanation for correct answer:

1. The momentum is given by, $p=mv$, where m is the mass and v is the velocity.
2. So when the speed (v) is doubled since momentum varies directly with speed/velocity, momentum is also doubled.

Explanation for incorrect answers:

1. Acceleration is defined as the rate of change in velocity, which requires the concept of time to be studied along with time.
2. Kinetic energy is given by, $k=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.m{v}^2$ where m is the mass and v is the velocity. Hence, when speed is doubled, Kinetic energy increases by four times.
3. Potential energy is given by, $P=mgh$, where m is the mass, h is the height to which it is raised and g is the acceleration due to gravity. Hence, potential energy is independent of the speed of the body.

Therefore, option (B) is the correct answer.