Question

What does the principle of conservation of linear momentum state?
(a) The linear momentum of a system cannot be changed
(b) The linear momentum of a system cannot remain constant
(c) The linear momentum of a system can be changed only if internal forces act
(d) The linear momentum of a system can be changed only if external forces act on it

Answer 1

Hint : Linear momentum of a body is the product of mass and velocity of the body. Linear momentum is the characteristic of a linear motion. The same force applied for the same time causes the same change in linear momentum in bodies of different masses.

Complete step by step solution: The principle of conservation of linear momentum states that the linear motion of a system can be changed only when external forces act on it. The linear motion of a particle is defined as the product of the mass of the velocity of that particle. Mass is always conserved for a system. The conservation of momentum of a particle is a property exhibited by any particle where the total amount of momentum never changes. Linear momentum of a particle is a vector quantity and is denoted by P.

Hence, option D is correct.

Additional information: The conservation of linear momentum, the general law of physics according to which motion, called motion, never changes into a separate collection of objects; That is, the total speed of a system remains constant. Emotion is equal to the mass of an object multiplied by its velocity and the force required to stop an object in one unit length. For any array of multiple objects, the total speed is the sum of the individual momentum. One peculiarity, however, is a vector amount in motion, which includes both the direction and magnitude of motion, so that the momentum of objects moving in opposite directions can cancel out the overall sum of zeros.

Note: Principal of conservation of linear momentum: In an isolated system, mutual forces between pairs of particles in the system can cause changes in linear momentum of individual particles. But as the mutual forces for each pair are equal and opposite, the linear momentum changes cancel in pairs, and the total linear momentum remains unchanged.
This principle is an important consequence of second and third laws of motion.
The law is universal and holds good, whether the motion is elastic/inelastic.