The force that one surface exerts on another when the two rub against each other is called
a. friction.
b. acceleration.
c. inertia.
d. gravity.

the law of universal gravitation states that any two objects in the universe that have mass, without exception,
a. attract each other.
b. repel each other.
c. combine to provide a balanced force.
d. create friction.

answer both

a is the best answer your welcome

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.