Advertisements
Advertisements
प्रश्न
Akhtar, Kiran and Rahul were riding in a motorcar that was moving with a high velocity on an expressway when an insect hit the windshield and got stuck on the windscreen. Akhtar and Kiran started pondering over the situation. Kiran suggested that the insect suffered a greater change in momentum as compared to the change in momentum of the motorcar (because the change in the velocity of the insect was much more than that of the motorcar). Akhtar said that since the motorcar was moving with a larger velocity, it exerted a larger force on the insect. And as a result the insect died. Rahul while putting an entirely new explanation said that both the motorcar and the insect experienced the same force and a change in their momentum. Comment on these suggestions.
Advertisements
उत्तर
According to the law of conservation of momentum:
Momentum of the car and insect system before collision = Momentum of the car and insect system after collision
Hence, the change in momentum of the car and insect system is zero.
- Kiran's fallacy is that the magnitude of change in momentum of the insect is much greater than the magnitude of change in momentum of the car. His argument is wrong. The velocity of the car was very high; basically, the car applied a lot of force on the insect, Akhtar's argument is also wrong.
- Rahul's argument is correct. Equal force is applied to both because reaction is opposite to action. Also, the magnitude of change in momentum is also the same, while momentum is conserved during collision.
- Akhtar made a correct conclusion because the mass of the car is very large as compared to the mass of the insect.
APPEARS IN
संबंधित प्रश्न
Explain the meaning of the following equation : .
p = m x v
where symbols have their usual meanings.
Which physical quantity corresponds to the rate of change of momentum ?
Fill in the following blanks with suitable words :
In collisions and explosions, the total _____________ remains constant, provided that no external _____________ acts.
A gun of mass 3 kg fires a bullet of mass 30 g. The bullet takes 0.003 s to move through the barrel of the gun and acquires a velocity of 100 m/s. Calculate:
- the velocity with which the gin recoils.
- the force exerted on gunman due to recoil of the gun
Explain why, a cricket player moves his hands backwards while catching a fast cricket ball.
A 150 g ball, travelling at 30 m/s, strikes the palm of a player’s hand and is stopped in 0.05 second. Find the force exerted by the ball on the hand.
Why would an aircraft be unable to fly on the moon ?
A girl of mass 50 kg jumps out of a rowing boat of mass 300 kg on to the bank, with a horizontal velocity of 3 m/s. With what velocity does the boat begin to move backwards ?
A truck of mass 500 kg moving at 4 m/s collides with another truck of mass 1500 kg moving in the same direction at 2 m/s. What is their common velocity just after the collision if they move off together ?
A man wearing a bullet-proof vest stands still on roller skates. The total mass is 80 kg. A bullet of mass 20 grams is fired at 400 m/s. It is stopped by the vest and falls to the ground. What is then the velocity of the man?
