Question

When a carpet is beaten dust raises up/falls down. Why? Is it Newton's First Law or Third Law.

Answer 1

Newton's First law states that the body at rest will remain at rest and body in motion will continue to do motion in a straight line unless an external force is applied on it.
Now coming to the question, Carpets contains dust particles which are at rest. When we beat up the carpet, the carpet moves sideways due to an external force(inertia of motion) but the dust particles which are at rest will remain at rest by Newton's first law of motion. When the carpet moves sideways, the dust particles which are at rest will stay at rest and it will seem to us that dust particles are coming out of carpet but the dust particles does not change their position because of inertia of rest. When the particles come out, they free fall on the ground.
But when we try it with a duster we can observe dust particles moving up and duster is made to move from upwards to downwards but we can observe dust particles moving upwards as newtons 3 rd law states that for all action there is an equal and opposite reaction it might be newtons first law but it possess first third law.