They affect the acceleration of bodies.
Gravity and friction there are others also like magnetism for example..
Normal, Friction, Tension, and Elastic Forces.
Contact forces must be touching whatever they are acting on the others have a field of influence around them; ie they don't have to touch to act on something
They are forces of nature..
friction forces
friction
Sliding Friction
Friction produces heat. The other forces produce motion or stress.
They are forces of nature.
Mainly friction.
Friction
Four forces in static friction are:- 1. Weight 2. Tension 3. Normal Force 4. Static Friction