Force needed to move a free floating object through space

Ryan Delaney

This is going to sound like a really simple question but i was wondering if there is an equation to calculate the force needed to move an object through outer-space

Ryan D

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K^2

You don't need any force to move an object. You only need force to accelerate an object. Once it's going, it will keep going at the same speed.

Ryan Delaney

so say you're trying to move a free floating planet what would the word be to get it moving

p.s. eventually i want to be able to calculate it with all the other planets and breaking out of orbit

K^2

If you apply a constant force to an object, you will get constant acceleration given by Newton's 2nd law. F = ma, where m is the mass of the object. In principle, any amount of force will get an object moving as fast as you need if given enough time. In practice, you want it done in some finite amount of time. Under constant acceleration, Δv = at. So if you have change of velocity Δv, in mind that you want to achieve in some time t, the force required is given by F = mΔv/t. In the process, you will expend at least E = (1/2)mv² of energy, which will be equal to the kinetic energy of the body. If you plan to use rockets, or something like that, you will use up a lot more energy, but in space, you rarely have a way to get around that.

For orbital motion, there are many nifty shortcuts. If you outline what you want the final problem to look like, I might have better suggestions.

Ryan Delaney

the basis of the problem is that i want to see if it would be possible to move a moon of Jupiter Europa to earth orbit without creating gravitational problems but first i have to see how to get it moving and how much energy is needed then there is the planets along the way that will most likely cause more energy to be expended

polka129

good insight K2.a question.how can we calculate the force exerted on an object when we only know the kinetic energy it possess and nothing else?.

If you apply a constant force to an object, you will get constant acceleration given by Newton's 2nd law. F = ma, where m is the mass of the object. In principle, any amount of force will get an object moving as fast as you need if given enough time. In practice, you want it done in some finite amount of time. Under constant acceleration, Δv = at. So if you have change of velocity Δv, in mind that you want to achieve in some time t, the force required is given by F = mΔv/t. In the process, you will expend at least E = (1/2)mv² of energy, which will be equal to the kinetic energy of the body. If you plan to use rockets, or something like that, you will use up a lot more energy, but in space, you rarely have a way to get around that.

For orbital motion, there are many nifty shortcuts. If you outline what you want the final problem to look like, I might have better suggestions.

chingroy

the basis of the problem is that i want to see if it would be possible to move a moon of Jupiter Europa to earth orbit without creating gravitational problems but first i have to see how to get it moving and how much energy is needed then there is the planets along the way that will most likely cause more energy to be expended

the only possible way of doing so, would be to dislodge Europa from the gravitational forces of the planet jupiter, mere than a simple nudging force...perhaps the answer lays in creating a gravitational anomaly in subspace around the object itself and then creating some type of minor implosion once the forces of gravity are counter acted, Roy C, Silva

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