Final answer:
Contact forces such as the force of friction and the force of a glove on a punching bag are examples of normal forces.
Step-by-step explanation:
Contact forces such as the force of friction and the force of a glove on a punching bag are examples of normal forces. Normal force is the force exerted by a surface to support the weight of an object in contact with it. In the case of the force of friction, it is the normal force between two objects that determines the strength of the frictional force.