What is second law of motion? explain?
Newton's second law explains what happens to an object when a non-zero net force acts on it. The second law states that the rate of change of momentum is directly proportional to force applied. So Newton's second law of motion is based on momentum
Newton’s Second Law states that if the forces acting on a body is balanced (or cancel each other out) then the body won’t accelerate in any direction. If the forces are unbalanced, the object will accelerate at a rate that’s equal to the force applied (or resultant force) divided by the object’s mass.
An example of when the forces are balanced can be performed by you by simply standing up. The force of gravity is pulling you down to the ground but the ground resists, causing it to create a reaction force in the opposite direction to balance the forces. This causes you to stay standing still and not sink into the ground or float away.