Identify the incorrect statement :

No work is done by a force F on an object if :

1. the object is stationary but the point of application of force moves on the object.
2. the object moves in such a way that the point of application of force remains fixed.
3. the force is always perpendicular to velocity.
4. the force is always perpendicular to acceleration.

A coolie A takes 1 minute to lift a load to the roof of a bus whereas coolie B take 2 minutes to lift the same load to the roof of the same bus. The work done by B is:

1. equal to work done by A
2. greater than work done by A
3. less than work done by A
4. none of the above.

A block of mass 20 kg is pulled up a slope as shown in the figure given below with a constant speed by applying a force of 200 N parallel to the slope from the initial position A to the final position B. Work done in moving the block from A to B is:

1. 600 J
2. 500 J
3. 60 J
4. 200 J

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 ?

1. 20 J
2. 40 J
3. 60 J
4. 80 J