Concepts Of Physics MCQ Edition [Volume 1]
- Exam
- Concepts Of Physics MCQ Edition [Volume 1]
- Subject
- Physics
- Chapter
- Friction
Concepts Of Physics MCQ Edition [Volume 1] · Physics · Friction
A vehicle is travelling towards the east on a horizontal road....
A vehicle is travelling towards the east on a horizontal road. Neglect any forces exerted by the air. The frictional force exerted by the road on the vehicle
Options
- Ais towards the east if the vehicle is accelerating
- Bmust be towards the east
- Cmust be towards the west
- Dis zero if the vehicle moves with a uniform velocity
Correct answer
D. is zero if the vehicle moves with a uniform velocity
Step-by-step solution
Since air resistance is neglected, the only external horizontal force acting on the vehicle is the frictional force exerted by the road.
According to Newton's second law, the net horizontal force is given by .
If the vehicle is accelerating, its speed is increasing in the direction of motion (east). The acceleration is towards the east, so the net force, which is the frictional force, must be towards the east.
If the vehicle moves with a uniform velocity, its acceleration is zero (). Therefore, the net horizontal force must be zero, which means the frictional force exerted by the road is zero.
If the vehicle is decelerating (applying brakes), the acceleration is towards the west, so the frictional force would be towards the west. Hence, the frictional force does not always act in a fixed direction.
According to Newton's second law, the net horizontal force is given by .
If the vehicle is accelerating, its speed is increasing in the direction of motion (east). The acceleration is towards the east, so the net force, which is the frictional force, must be towards the east.
If the vehicle moves with a uniform velocity, its acceleration is zero (). Therefore, the net horizontal force must be zero, which means the frictional force exerted by the road is zero.
If the vehicle is decelerating (applying brakes), the acceleration is towards the west, so the frictional force would be towards the west. Hence, the frictional force does not always act in a fixed direction.