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#91 - vickachu
Reply +7 123456789123345869
(07/05/2013) [-]
how much energy would there be needed to stop something as big as our planet from spinning?
#111 to #91 - mralice
Reply +17 123456789123345869
(07/05/2013) [-]
Assuming you mean spinning, and not orbiting...

Newtons second law of motion is Force = (Mass)(Acceleration). F=MA.

Earths mass is roughly 5.9736 × 10^24 kg (according to Google).

The Earths acceleration is 0.03 m/s2 (soruce at tinyurl.com/fjscience).

So... 1.79208 x 10^23 Newtons of force would be needed at the exact opposite vector the Earth is spinning in.
1 N is 0.1225 lbs so you would need a force of 21,952,980,000,000,000,000,000 pounds.
User avatar #251 to #111 - zigap
Reply 0 123456789123345869
(07/05/2013) [-]
Physics gets a lot more ****** up if stuff is rotating.

Plus, you calculated the force that would be required to stop the earth from accelerating, not stoping it.
#243 to #111 - anon
Reply 0 123456789123345869
(07/05/2013) [-]
This problem requires rotational mechanics, i.e. mass is replaced with moment of inertia, force by moment and momentum but angular momentum. Besides, stopping linear movement by applying a force also requires time.
But to the question at point:
Earth's mass: me=5,97e24 kg
Earth's radius: R=6,38e6 m
Moment of inertia: K=(2/5)*M
e*R^2=9,72e37 kgm^2 AeB means A*10^B Now we need the moment, which is force F multiplied by R: M=F*R (note: M=/=m_e)
BUT: in relation to Newton's 2nd: M=dL/dt, in which dL=change of angular momentum L; dt=change of time. Angular momentum L=w*K, in which w=2*pi*f and f is Earth's spinning frequency (once every 24h)-> w=pi/43200 1/s
We get F*R=dL/dt -> F=dL/(r*dt) dL=-9,72e37*(pi/42300) 1/s =-7,07e33 We can forget the minus sign since we aren't calculating vectors. Let's make an assumption: we want to stop Earth in exactly 1 second -> dt=1s -> F=7,07e33/6,78e6=1,043e27 Newtons for 1 second at the equator stops the Earth's spinning.

Physics undergrad out.
#103 to #91 - McCockAFucker
Reply +1 123456789123345869
(07/05/2013) [-]
the earths mass is 5.97219 × 10^24 kilograms. and you need to have the centripetal force of the earth or some **** (got it off the internet so dont think im smart enough to figure this out) multiplying it would result in the force required to stop it from spinning being 9.9577042267626e+21kg
User avatar #93 to #91 - emptysuperman
Reply +103 123456789123345869
(07/05/2013) [-]
User avatar #209 to #93 - ghettograndpa
Reply 0 123456789123345869
(07/05/2013) [-]
Wasn't the answer to all things 42?
User avatar #212 to #209 - brutallyhonest
Reply 0 123456789123345869
(07/05/2013) [-]
What becomes before 42?
User avatar #214 to #212 - ghettograndpa
Reply -1 123456789123345869
(07/05/2013) [-]
Jesus and the Six Guardians of the gate of Hell