Question

Consider a car parked on a hill and pick the axis of rotation (i.e., the pivot point) to pass through the points where the front tires touch the ground. The weight of the car exerts a torque about this axis. What other forces on the car will also exert a torque about this same axis?
(a) The forces of friction on the back tires only.
(b) The forces of friction on both the front and back tires.
(c) The normal forces on the front tires of the car.
(d) The normal forces on the back tires of the car.
(e) The normal forces on both the front and back tires.

Answer 1

Answer:d

Explanation:

Torque of Frictional force will be zero

$\tau _{f_1}=zero$

$\tau_{f_2}=zero$

because they passes through line of action

Torque of Weight is $T=W\times x$

The other force which will create torque about Pivot point is Normal Force on second tire

Torque due to Normal Reaction $\tau _N=N_2\times y$

Thus Normal Force on back tires of car will create torque about this same axis.