The energy of electron is 2.5 eV. When expressed in Joule, it is

1. 1.6 x 10^-19 J
2. 4.0 x 10^-19 J
3. 3.2 x 10^-19 J
4. 0

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

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.

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true but R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

Assertion (A): Work done by frictional force is negative.

Reason (R): This is because frictional force acts along the direction of motion.

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true and R is not the correct explanation of A
3. Assertion is false but reason is true
4. Assertion is true but reason is false