General Knowledge - Basic General Knowledge - Discussion

Take a cosco ball and dip it in water. Take it out and slowly rotate it, and then rotate it fast, when you rotate it slow nothing will happen but when you rotate it fast water will sprinkle out.

Same is the case with earth if it starts rotating fast the objects on it will be pushed outside but the gravitational pull will hold them. Hence the weight will be reduced. :-).

Force(centripetal force = mvr where m is the mass of the body and v is the velocity ie speed) remains same. So when v increased, m decreases.

Dear Friends. This is all about the formula E= mc(square). Try to recall and calculate that. In short " when a body travels with the speed of light it gets converted into energy (in short mass or weight reduces) Clear?

I'm sorry if that was too technical an explanation, I do realise this was a General knowledge question but that seemed like the most legit explanation.

A little bit of physics will tell you that the speed of rotation of the earth has a direct effect on acceleration due to gravity.

And Acceleration due to gravity in turns affects the weight because weight=mass*acceleration due to gravity.

A simple equation gives us the relation between acceleration due to gravity and angular velocity of the earth which is g'=g-rw^2
Where g' = resultant acc due to gravity.
g = acc due to gravity on surface of the earth (= 9.8 m/s^2).
r = radius of the earth.
w(omega) = angular velocity of earth I.e. velocity at which earth is rotating about its axis.

This simply means that greater the w(omega) lesser would be g' and consequently lesser would be the weight.

Hope that makes things a little more clear.
P.S.The equation is derived in class 11 physics of any board.

As we all know energy(E)=1/2MV^2 and weight=Mg

So from the first equation we can get M=2E/V^2. Then put this value in second equation, so now the result comes weight(W)=2E/gV^2. So,if V increases then W decreases.

Weight shuold remain constant. Because being in inertial frame. No effect on body's weight should take place.

Weight=m*g (in general case).

Now as the earth rotates with more speed it is likely to produce more centrifugal force as per mv^2/r as we (velocity) will increase as stated. Are (radius of earth) remains constant.

Now centrifugal force tries to cancel out the gravity force (basic concept). The increase in centrifugal force will try to decrease weight of body which is essentially nothing but gravity's effect on mass.

If you observe the same principle is used in satellites, as they rotate with certain speed they come under earth's gravitation field or in other words they cancel out gravitation force which is trying to bring satellite on the earth.

I have some doubt in Akshay's answer. If centrifugal force trying to pull the body outside then the centrifugal force on the body increases. Then why don't we add centrifugal force to the weight. And why do we need to add centrifugal force to weight.

Good Explanation.