PHYSICS XI Ch#3 Quiz 3

A Motorcycle safety helmet is padded so as to extends the time of collision which results in decreasing the impulse to prevent us from serious injury.

As object is moving downward with neglecting all the frictional effects (air rsistance) then it is moving under the acceleration due to gravity, therefore its motion is said to be free fall motion.

At maximum height the velocity completely becomes horizontal (along x-axis) and acceleration (due to gravity) is vertivally downward so they become mutually perpendicular (90˚) to eacxh other.

If all the other resistive effects are neglected then due to same value of gravitational acceleration (g) both will reach at the same time.

Time rate of change of momentum of a body is equals to the applied- force.

In this case

As the object is freely falling so the force acting on the object is equal to its weight. Therefore, the rate of change of momentum of a freely falling body is equal to its weright.

Projectile wiil bounce back with the same velocity while target will remain stationary (velocity remains zero). This fact is made used of by the squash player.

A typical rocket ejects burnt gases at speed over 4000 m/s or 4 km/s

As 

Impulse = Fxt

Units;

Unir of Impulse = (Newton)x(second)

Unit of Impulse = N s