Question

For a projectile momentum conservation formula can not be applied because external force gravity is acting?

Answer 1

Hi,

This statement is false.

Gravity is an internal force because it could exist between two objects even when they are not physically touching. The forces are categories on the basis whether or not their presence is capable of changing an object's total mechanical energy. External forces include normal force, tension force, friction force, and air resistance force and internal forces include the gravity forces, magnetic force, electrical force, and spring force. In projectile motion, we assume that air resistance is zero. Thus, we can apply momentum conservation formula in projectile motion as there is no external force.