Question

8) T F A car is being towed at constant velocity on a horizontal road using a horizontal chain. The tension in the chain must be equal to the weight of the car in order to maintain constant velocity.

Answer 1

Answer:

False

Explanation:

The tension in the chain must be equal to the frictional force acting on the car, not to its weight.

In fact, we have 4 forces acting on the car

- Its weight: downward

- The normal reaction of the road on the car: upward --> this force balances the weight, so the net force along the vertical direction is zero

- The tension in the chain: forward

- The frictional force between the road's surface and the tires of the car: backward

We can consider the horizontal motion only: we are said that the car is moving at constant velocity, so the horizontal acceleration is zero. According to Newton's second law:

$\sum F = ma$

zero acceleration means that the resultant of the forces on the car is zero. But there are only 2 forces acting on the car in the horizontal direction: the tension in the chain (forward) and the frictional force (backward). Since their resultant must be zero, it means that the two forces must be equal and opposite: therefore, the tension in the chain must be equal to the frictional force.