Question

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:
This question has multiple correct options.
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 rear wheels has larger magnitude than the friction on the front wheels.

Answer 1

Hint:First of all, we have to analyze the rotation of the wheel in terms of motion, friction, and acceleration, then we obtain the required answer. We need to examine the direction of friction, which is opposite to the motion of the object.

Complete answer:
The wheel attempts to push the ground back in the rear-wheel-drive, thereby gaining a frictional force in the forward direction. The car then moves the front wheel, thereby gaining a frictional force in the backward direction that initiates the front wheel's rolling motion. The force which accelerates the car forward is the static friction force acting on the rear wheels. It is substantially larger since the entire mass of the car has to be shifted, while the friction force on the front wheels has to provide just adequate torque to provide the right angular acceleration to the front wheels.
Explanation:
For option A: Since the motion is favored and the car accelerates in the forward direction.
For option B: The road applies friction force in the backward direction because of the car's motion in the forward direction, the direction of the front wheels and in reaction.
For option C: If the vehicle travels in the forward direction, the friction force of the rear wheels is greater (in the forward direction) than that of the front wheels.
The correct options A, B and C.

Additional information:
Motion: Motion in physics is the process in which an object, over time, changes its location. In terms of displacement, distance, velocity, acceleration, speed and time, motion is mathematically defined.
Acceleration: In mechanics, acceleration is the rate at which an object's velocity varies in relation to time. Accelerations are (in that they have magnitude and direction) vector quantities. The orientation of the acceleration of an object is provided by the orientation of the net force which acts on that object.
Friction: Friction is a force between two surfaces that slide across each other or attempt to slide. When you try to maneuver a book along the concrete, for instance, friction makes this difficult. In the direction opposite to the direction in which the object is moving, or attempting to move, friction still works.

Note:The force which accelerates the car forward is the static friction force acting on the rear wheels. It is substantially larger since the entire mass of the car has to be shifted, while the friction force on the front wheels has to provide just adequate torque to provide the right angular acceleration to the front wheels.