Which is what you get when you set the gravitational and centripetal force terms equal, which has already been discussed. (since g = Gm/R²)

ok, sorry then, I just had no time to look at all the posts!

Because you're balancing the weight of the bullet with the centripetal acceleration. So the mass doesn't enter into it.

 

Just plain not true. I'm balancing weight with centripetal FORCE as well I should.

 

You sure Swansont? I thought the potential energy would be positive, and I seem to get the right answer. If increasing height made PE drop, wouldn't conservation make KE increase, so as you move upwards, you constantly accelerate?

yes but the mass term cancels.

Just plain not true. I'm balancing weight with centripetal FORCE as well I should.

 

You sure Swansont? I thought the potential energy would be positive, and I seem to get the right answer. If increasing height made PE drop, wouldn't conservation make KE increase, so as you move upwards, you constantly accelerate?

 

psst weight and centripetal force are the same thing.

Just plain not true. I'm balancing weight with centripetal FORCE as well I should.

 

You sure Swansont? I thought the potential energy would be positive, and I seem to get the right answer. If increasing height made PE drop, wouldn't conservation make KE increase, so as you move upwards, you constantly accelerate?

 

PE = -GMm/r, assuming PE = 0 infinitely far away. You have to add energy to increase r

what?

 

maybe in this particular example they are equal, but that is not true in the general case, just feel your chair pressing into you, they are crtainly not the same thing in any instance.

CPL that is because there is a force counteracting the centripetal force.

 

the centripetal force(weight) is the same but the net force is nigh on zero because of the counteracting force of the chair.

That what I said, centripetal force is equal to weight, not centipetal acceleration as gareth said, so the m's cancel. If it were acceleration, we would be left with an m in the weight term.

 

I was being very stupid with the energy admittedly :$