CBSE Class 9 Physics Force and Laws of Motion
Force
Force is defined as push or pull.
Friction force resists motion between two objects that are in contact with each other.
If the resultant of all the forces acting on a body is zero, the forces are called balanced forces and if the resultant of all the forces acting on a body is non zero, the forces are called unbalanced forces.Newton's First Law of Motion
Newton's first law of motion: A body at rest will remain at rest and a body in motion will remain in uniform motion unless acted upon by an unbalanced force.
The property by the virtue of which an object tends to remain in the state of rest or of uniform motion unless acted upon by some force is called inertia.
The mass of a body is a measure of inertia.Newton's Second Law of Motion
The momentum of a body is defined as the product of its mass and velocity.
Newton's second law of motion states that the rate of change of momentum of a body is directly proportional to the force and takes place in the same direction as the force.
Force is also defined as the product of mass and acceleration.Newton's Third Law of Motion
Newton's Third Law of MotionConservation of Linear Momentum
Law of conservation of momentum states that the sum of momenta of the two objects before collision is equal to the sum of momenta after the collision provided there is no external unbalanced force acting on them.
The velocity with which the gun recoils in the backward direction is known as recoil velocity
