Question

The first law of motion can be obtained from the second law of motion if we set the condition that there is no force acting. Nevertheless, the first law of motion is described independently of the second law. Explain the reason behind this

Answer 1

according to second law, acceleration is directly proportional to the applied force

ie F = ma = m(v2-v1)

if Force is zero

then m(v2-v1) = 0

or mv1= mv2

or v1= v2

this is first law of motion, which states that, if a body is in motion, will remain in motion in same direction and with same speed, and if a body is at rest will remain at rest untill and unless, external force is applied to change the state of motion or rest.

but first law doesnt depend on second law, infact vice versa is true, because we are talking about state of motion of an object under zero net force , but in second law we observe the effect of force thats why it is also known as force law