Question

Explain two ways in which an air bag changes the force on your body to make you safer during a collision.

How can you use Newton's force laws to explain the way a rocket works? Be as specific as you can. How would you describe the way a rocket works using the concept of momentum?

Answer 1

1) Change in momentum =impulse = F x dt

Hence during collision momentum changes as we decelerate from some initial velocity.This happens in very short time dt.

Hence Force' F ' will be much higher.This factor will be extremely harmful for driver.

2) Pressure =Force /Area

Airbags provides large surface area.hence pressure will be reduced.

Newton's 3rd law states that,'For every action there is always an opposite and equal reaction.'

A rocket can lift off from a launch pad only when it exhaust gas out of its engine.The rocket pushes on the gas, and the gas in turn pushes on the rocket.

This works on "Conservation of momentum'.

m1v1 = m2v2 ........m1 and m2 are mass of Gas and rocket,v1 and v2 are the velocities.the rocket fuel is burns continuously.Hence total mass of gas must be considered which burned in that time.

Momentum is given to the exhaust gases in one direction so the rocket itself must gain momentum in the other direction.