Question

A projectile is fired at ${30}^0$, with momentum $p$. Neglecting friction, the change in kinetic energy when it returns to the ground, will be:-

• A. $Zero$
• B. $30\%$
• C. $60\%$
• D. $100\%$

Answer 1

The correct option is A $Zero$

When the projectile return back to the ground its vertical velocity has changed the direction but the magnitude remains the same and horizontal velocity remains same all the time so kinetic energy being a scalar quantity does not change as magnitudes of mass and velocity are unaltered.
So change in K.E. is Zero.