Question

In a head-on elastic collision of a very heavy body moving at $v$ with a light body at rest, the velocity of the heavy body after the collision is:

• A. $v$
• B. $2v$
• C. zero
• D. $\frac{v}{2}$

Answer 1

The correct option is A

$v$

Correct Option:

Option A

1. A collision between two objects in which the kinetic energy of the masses remains the same is called elastic collision.
2. In a perfectly elastic collision there is no change in net kinetic energy.
3. Since $KineticEnergy=\frac{1}{2}\times mass\times velocit{y}^2$ and the mass of the objects remain same, there is no change in the magnitude of velocity of the object in a perfectly elastic collision.
4. So, in a perfectly elastic collision there is no change in magnitude of velocity but the direction reverses.
5. Hence, the velocity will remain to be $v$.

Option B

The velocity of the body will remain unchanged. So, it will not be $2v$.

Option C

The velocity of the body will remain unchanged. So, it will not be $0$.

Option D

The velocity of the body will remain unchanged. So, it will not be $\frac{v}{2}$.

Hence, option A is correct.