Physics
Assertion (A): Work done by frictional force is negative.
Reason (R): This is because frictional force acts along the direction of motion.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is false but reason is true
- Assertion is true but reason is false
Work, Energy & Power
1 Like
Answer
Assertion is true but reason is false
Explanation
Assertion (A) is true because friction acts opposite to the direction of displacement of the object. Since work depends on the angle between the force and the displacement and a force acting opposite to motion makes an angle of 180° which produces negative work.
Reason (R) is false because friction does not act along the direction of motion; it acts opposite to the direction of motion.
Hence, assertion is true but reason is false.
Answered By
2 Likes
Related Questions
The graph given below shows a force-displacement graph. What is the total work done by force on the body in displacement from x = 0 to x = 6 m ?
- 20 J
- 40 J
- 60 J
- 80 J
Assertion (A): When the displacement is normal to the direction of force, the work done is zero.
Reason (R): Work done depends on the angle between force and displacement.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true but R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
A force F acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of force.
(a) Write the expression for the work done by the force.
(b) What should be the angle between force and displacement so that the work done is (i) zero, (ii) maximum?
A body is moved in a direction opposite to the direction of force acting on it. State whether the work is done by the force or work is done against the force.