A tow truck is towing a car. As it descends down a hill, the tow truck driver has to apply his brakes to slow both the car and truck. While he is applying his breaks, compare the force that the tow truck applies to the car, Ft-c, to the force that the car applies on the tow truck, Fe-t

Newton’s Third Law and Towing Forces

Question

A tow truck is towing a car. As it descends down a hill, the tow truck driver applies the brakes to slow both the tow truck and the car. While the brakes are applied, how does the force that the tow truck applies to the car (F_truck→car) compare to the force that the car applies to the tow truck (F_car→truck)?

Answer

Detailed Explanation

This situation is a classic illustration of Newton’s Third Law of Motion, which states:

This law means that whenever one object exerts a force on a second object, the second object exerts a force of the same magnitude in the opposite direction on the first object.

In this scenario:

• The tow truck applies a force forward on the car through the connecting chain or hitch. This force attempts to slow or control the car as both vehicles descend the hill.
• At the same time, the car applies an equal force backward on the tow truck. This opposing force is a direct consequence of Newton’s third law.

Mathematically, this can be expressed as:

F_truck→car = – F_car→truck

The negative sign indicates that the directions are opposite.

It does not matter that the vehicles are moving downhill or that the brakes are being applied; the mutual forces remain equal and opposite because they are part of the same interaction pair.

Conclusion

Therefore, the force that the tow truck applies to the car is equal in magnitude to the force that the car applies to the tow truck, in perfect accordance with Newton’s third law.