Final answer:
The force that allows a car to tow a trailer is tension, which acts along the hitch connecting them. Other forces such as gravity, friction, and air resistance affect the towing, but tension is the primary towing force.
Step-by-step explanation:
The type of force that allows a car to tow a trailer is tension. Tension is a force that acts along a stretched flexible connector, such as a rope or cable, between two objects. In the context of a car towing a trailer, the force in the hitch connecting the two can be considered a tension force. This tension force allows the car to apply a force to the trailer, dragging it along. Other forces such as gravity, friction, and air resistance also play a role in towing a trailer, but the direct force that enables the towing is tension.
When a car tows a trailer, there is a force resisting the motion which can be calculated by applying Newton's second law of motion, taking into account the mass of both the car and the trailer as well as the acceleration required. To troubleshoot problems in physics related to forces, one must often consider various forces like tension, gravity, normal force, friction, and others in a free-body diagram to understand all forces acting on an object.