Why does a sprinter keep running for sometime even after crossing the finish line?

Why does a sprinter keep running for sometime even after crossing the finish line?

Ans: – When the running for the sometimes then thee works moment of inertia and in the sprinter, case there also works this simple formula. When the printer crosses the finishes line then also this moment of inertia moves it to some distance.

 

Why is it advised to tie the luggage with a rope on the roof of busses?

Ans: – When the bag is tied with the rope above the bus it stops the inertia motion of the bags after the starting of the bus. So,these bags remain in its position because of tied it.

 

Why do the dust particles from the hanging blanket fall off when it is beaten with a stick?

Ans: – The dust particles in a blanket try to maintain in states of motion but the shaking of the blanket makes the particles moves around. So, the inertia of the particles does that job.

 

State Newton’s first law of motion. Why do the passengers standing in a stationary bus fall in the backward direction when the bus begins to move suddenly?

Ans: – The Newton first law of motion stats that if we don’t exert pressure from the outside then the moving particles and the object which is in its position always try to remain in its position.

As a result of that we see the bus when suddenly move our body also moves in that direction because of moment of inertia.

Define momentum. How the rate of change of momentum is related to force?

Ans: – The momentum is the multiplication of the mass and the velocity. As we all know that forces depend on the mass and the acceleration which is dependent on the velocity so changes in the momentum makes the forces changes.

 

If a body of mass 10 kg moves with a velocity of 7 ms–1, then what is the momentum of the body?

Ans: – Momentum= mass × velocity

Or, momentum= 10 × 7= 70.

 

If a force of 50 N acts on a body of mass 10 kg then what is the acceleration produced in the body?

Ans: – We know that force, F= m × a.

Here, a = acceleration=?; mass=10kg, f=50N.

So, 50= a × 10;

Or, a=5 m/s^2.

 

State Newton’s third law of motion. Why it is difficult for a fireman to hold ahose pipe which ejects larger amount of water at a high speed?

Ans: – Newton third law states that each force has will has equal and opposite forces.

When the water is ejected from the hose pipe at that time each amount of force is needed from the hand to hold it. As the hand doesn’t provide same number of forces it is difficult to hold it.

 

“Action and reaction forces are equal in magnitude and opposite in direction”. Then, why do they not balance each other?

Ans: – Although the action and reaction forces are equal in magnitude and opposite in direction but all times that forces aren’t balanced. Because of the different number of sources of forces the action and reaction forces are not equal.

 

A motorcycle is moving with a velocity of 72 km/h and it takes 6 s to stop after the breaks are applied. Calculate the force exerted by the breaks on the motorcycle, if its mass along with the rider is 175 kg.

Ans: – Initial velocity(u)= 72 km/h = 72×5/18 = 20m/s.

Final velocity= 0; time=6s.

So, v= u + a×t,

Or, a=-20/6 =- 10/3.

Then force = mass× acceleration= 175× -10/3= 583.33N.

 

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