Question

assertion- newton second law gives the measurement of force . Reason- according to the Newton's second law of motion force is directly proportional to the rate of change of momentum​

Answer 1

$\underline{\bf\red{Question }}$

Assertion - Newton second law gives the measurement of force.

Reason - According to the Newton's second law of motion , force is directly proportional to change of momentum.

Answer -

Both the assertion and reason are correct and reason is the correct explanation for assertion.

Newton's second law of motion -

The rate of change of momentum is directly proportional to applied unbalanced forces.

Rate of change of momentum ∝ Force Applied

Let a body is moving with initial velocity u amd after applying a force F on it, the velocity becomes v in time t.

Inital momentum = $\rm p_1 = mu$

Final momentum = $\rm p_2 = mv$

Change in momentum in time t = mv - mu

So rate of change of momentum =

$\rm \frac{mv - mu}{t}$

But according to Newton's second law,

$\rm \frac{mv - mu}{t} \propto F$

$\rm F \propto \frac{m(v-u)}{t}$

$\rm \frac{v - u}{t} = a$

$\rm F \propto ma$

$\rm F = kma$ ( k is proportionality constant )

$\rm k = 1$

$\rm F = ma$

So the magnitude of resultant force acting on a body is equal to the product of mass of body and acceleration produced. Direction of the force is same as that of acceleration.

Answer 2

Answer:

Both the assertion and reason are correct and reason is the correct explanation for assertion