The Total solution for NCERT class 6-12
Akhtar, Kiran, and Rahul were riding in a motorcar that was moving with ahigh velocity on an expressway when an insect hit the windshield and got stuckon the windscreen. Akhtar and Kiran started pondering over the situation. Kiransuggested that the insect suffered a greater change in momentum as compared tothe change in momentum of the motorcar (because the change in the velocity ofthe insect was much more than that of the motorcar). Akhtar said that since themotorcar was moving with a larger velocity, it exerted a larger force on theinsect. And as a result the insect died. Rahul while putting an entirely newexplanation said that both the motorcar and the insect experienced the sameforce and a change in their momentum. Comment on these suggestions.
As per the law ofconservation of momentum, the total momentum before the collision between theinsect and the car is equal to the total momentum after the collision.Therefore, the change in the momentum of the insect is much greater than thechange in momentum of the car (since force is proportional to mass).
Akhtar’s assumption ispartially right. Since the mass of the car is very high, the force exerted onthe insect during the collision is also very high.
Kiran’s statement isfalse. The change in momentum of the insect and the motorcar is equal byconservation of momentum. The velocity of insect changes accordingly due to itsmass as it is very small compared to the motorcar. Similarly, the velocity ofmotorcar is very insignificant because its mass is very large compared to theinsect.