Newton’s First law of motion
A body at rest tends to remain at rest and a body in uniform motion tends to remain in the state of uniform motion until & unless an external force is applied on it.
For example, a ball lying on the table at rest will remain at rest until an external force is applied on it.
Balanced & Unbalanced forces :-Balanced Forces:
Equal & Opposite forces
Do not cause any change in motion
Can be in the same or opposite direction
Causes a change in motion
For example, in Tug of war, If teams 1 & 2 apply equal forces in opposite directions, there would be no net force. This is Balanced force.
However, if Team 1 exerts more force than Team 2, then there would be a net movement towards Team 1 and Team 1 would win. This is unbalanced force.
Newton’s first law was for scenarios where net force = 0. The second law is for scenarios with net force not equal to 0. Momentum plays a crucial role in Second law.
Momentum is the product of mass of a body & its velocity
It is a Vector quantity
It is denoted by p = mv
For example, A ball of 1 kg moving with 10m/sec has a momentum 10kg m/sec.
Momentum of a system remains conserved. Therefore,
Greater force is required to set heavier bodies in motion
Greater force is required to stop bodies moving with higher velocities
Greater the change in momentum in a given time, greater is the force that needs to be applied. In other words, greater the change in momentum vector, greater is the force applied.