Work done by the frictional force can be:
Correct answer: D. All of these
- A. Positive
- B. Zero
- C. Negative
- D. All of these
Explanation
Option D is correct. 1.The work done by the frictional force can be positive when the frictional force is in the same direction as the displacement of the object. This is because the frictional force has a component in the direction of the displacement, and therefore, work is done.For example: A box is sliding down a ramp. The frictional force between the box and the ramp is in the same direction as the displacement of the box. Therefore, the frictional force does work on the box, causing it to accelerate down the ramp. A block is being pushed up a hill. The frictional force between the block and the hill is in the opposite direction of the displacement of the block. Therefore, the frictional force does work against the block, causing it to slow down.2. The work done by the frictional force is zero when the frictional force is perpendicular to the displacement of the object. This is because the frictional force does not have a component in the direction of the displacement, and therefore, no work is done.For example:A car is moving on a horizontal road. The frictional force between the tires and the road is in the opposite direction of the displacement of the car. However, the frictional force is perpendicular to the displacement, and therefore, no work is done.3. The work done by the frictional force can be negative when the frictional force is in the opposite direction of the displacement of the object. This is because the frictional force has a component in the direction opposite to the displacement, and therefore, work is done against the object. For example: A block is being pushed up a hill. The frictional force between the block and the hill is in the opposite direction of the displacement of the block. Therefore, the frictional force does work against the block, causing it to slow down.
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About Work and Energy
Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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