gravity
repulsion force
thrust force
kinds of forces
Gravity is one of the four fundamental interactions observed in nature
The force is repulsive if the charges are of equal sign
frictional force
The thrust force is a force that occurs when a body is immersed in a fluid
the normal force F_n \, (or N) is defined as the force exerted on a body surface resting on it
The force is attractive if they are of opposite sign
force of attraction
