For a relation F = $\dfrac{m(Δv)}{Δt}$, to hold true, the condition(s) necessary is/are:

1. velocities are equal to the velocity of light
2. velocities are much smaller than the velocity of light
3. mass remains constant
4. both (b) and (c)

According to Newton's second law of motion, the change in momentum takes place in a direction :

1. opposite to the direction of force applied
2. perpendicular to the direction of the force applied
3. similar to the direction of the force applied
4. none of these

The S.I. unit of force is:

1. dyne
2. g cm s^-2
3. Newton
4. Joule

1 Newton is equal to :

1. 10³ dyne
2. 10⁸ dyne
3. 10¹⁰ dyne
4. 10⁵ dyne