Derivation
law of
conservation
of momentum

Applying Newton's third law, these two impulsive forces are equal and opposite i.e. If the time of contact is t, the impulse of the force F21 is equal to the change in momentum of the first object. The impulse of force F12 is equal to the change in momentum of the second object.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.