If there is no net external force
(push or pull in any direction), then every thing stays as it is. It
continues to stay at rest, if it is at rest. It continues to move with
the same speed if it is moving.
If i put a book on a table. the
net force acting on it is 0. so it stays as it is. A skating person on
ice, moves forward with same speed, if he/she does not press against the
ice, or shift the position.
The rate of change of
momentum is equal to the force acting on a body. OR, the force acting
on a body is equal to the product of mass and acceleration.
: it is the product of mass and velocity of the body. It gives the
total amount of velocity in the total body. It gives the total impact
the body will have if it collides with another object. It is also
related to the amount of force required to stop the body. If one with
higher momentum collides with another, one is hurt more.
If a body1 exerts a force F1 on another body2, then the body to exerts a force - F2 on body1 in the opposite direction.
two magnets are kept near each other with the north poles facing,
magnet1 exerts a force F1 on magnet2 and magnet 2 exerts a force = -F1
on magnet1. Magnet 1 moves backwards and magnet2 also move backwards.
wrestlers exert force F on each other through the hands. Each wrestler
is pushed backwards with force - F. But they remain stationary for some
time. How? A wrestler pushes the ground with force -F. The floor pushes
him forward with force F. The forces on the wrestler balance and he