Question

Newton’s law of motion gives the measure of
(A) Force
(B) Acceleration
(C) Momentum
(D) Impulse

Answer 1

Hint : The Newton’s second law of motion is the only Newton’s law which gives an absolute (quantitative) measure of a quantity. The law states that the net force acting on an object is directly proportional to the rate of change of momentum with time in which the body undergoes the motion.

Formula used: In this solution we will be using the following formula;
$F = \dfrac{{dp}}{{dt}}$ where $F$ is the force applied, $p$ is the momentum of the body, and $t$ is time taken to change momentum from one value to another.
$\dfrac{{dp}}{{dt}}$ signifies the instantaneous rate of change of momentum with time.

Complete step by step answer
The three laws of motion, one way or another, gives a statement about the nature of motion. However, of all the three, only the second law of motion gives an absolute measure of a quantity.
Newton's second law states that the force applied to an object is directly proportional to the rate of change of the momentum of that object with time, and this change in momentum takes the direction of that force.
It can be given mathematically as,
$F = \dfrac{{dp}}{{dt}}$ where $F$ is the force applied, $p$ is the momentum of the body, and $t$ is time taken to change momentum from one value to another.
$\dfrac{{dp}}{{dt}}$ signifies the instantaneous rate of change of momentum with time.
Hence, Newton’s law of motion gives a measure of force.
Thus, the correct answer is A.

Note
For clarity, it is quite tempting to think that Newton’s law of motion can also be a measure of acceleration, or momentum, or even impulse because each of them can be related to force. However this is not so, because even though all these quantities are contained in the law, these quantities are not expressed. For example, the law didn’t tell us about the nature of momentum, or that acceleration is the rate of change of velocity, nor did it tell us what impulse is.