In rear-wheel drive cars, the engine rotates the rear wheels and the front wheels rotate only because the car moves. If such a car accelerates on a horizontal road, the friction
(a) on the rear wheels is in the forward direction
(b) on the front wheels is in the backward direction
(c) on the rear wheels has larger magnitude than the friction on the front wheels
(d) on the car is in the backward direction.
(a) on the rear wheels is in the forward direction
(b) on the front wheels is in the backward direction
(c) on the rear wheels has a larger magnitude than the
Explanation:
When accelerating the torque on the rear wheel tries the part in contact with the road to slide backward so the friction on it is forward. Option (a).
The body of the car tries to push the front wheel in the forward direction, hence the force of friction is in the backward direction. Option (b).
The driving rear wheel has to produce a force in the forward direction (through the torque) to push the whole mass of the car while the torque on the front wheel has just to overcome the inertia of the wheel. Hence the friction on the rear wheel is more than the front wheel. Option (c). Net friction on the car is in forward direction because rear wheel friction is larger and in forward direction. Hence option (d) is not correct.