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
To bring a car to a halt over the shortest distance on a horizontal...
To bring a car to a halt over the shortest distance on a horizontal road, one must
Options
- Apump the brakes by alternately pressing and releasing them
- Bapply the brakes extremely hard so the wheels cease rotating
- Cturn off the engine without using the brakes
- Dapply the brakes firmly enough to just avoid slipping
Correct answer
D. apply the brakes firmly enough to just avoid slipping
Step-by-step solution
To stop the car over the shortest possible distance, the deceleration must be maximum.
The deceleration is provided by the frictional force between the tires and the road.
The maximum possible frictional force is the limiting static friction, which is greater than the kinetic friction ().
If the brakes are applied extremely hard, the wheels lock and slide, resulting in kinetic friction which provides less deceleration.
To utilize the maximum frictional force, the brakes should be applied firmly enough to just avoid slipping.
The deceleration is provided by the frictional force between the tires and the road.
The maximum possible frictional force is the limiting static friction, which is greater than the kinetic friction ().
If the brakes are applied extremely hard, the wheels lock and slide, resulting in kinetic friction which provides less deceleration.
To utilize the maximum frictional force, the brakes should be applied firmly enough to just avoid slipping.