INERTIA isn't a force, so it's....?
915321
Inertia means 'laziness' to changes\n\nso obviously,\nresistance to change in velocity,\nthe tendency to maintain constant velocity,\na property of matter,\n\nAll three of these choices qualify as applicable.\n'resistance to acceleration', means force is going to act to oppose the external  force..not property of inertia. ..got it right?
994962
Mass is kind of like the object's inherent inertia.  The inertia it would have regardless of its location and even if it were standing still.\n\nAn object's inertia is it's resistance to change.  Different things besides mass can affect an object's inertia.  For example, it's position can affect inertia, especially when talking about rotational motion.  An object located at a 1 meter wheel's rim has more inertia than an object located at the wheel's hub (lots more, in fact, since moment of inertia is equal to mass times the square of it's distance from the rotational axis).
288257
No force is needed to maintain motion.  You need a force to change motion: speed up, slow down, or change direction.
1051951
The forces that act on a roller coaster are Gravity, Friction, and a Centripital force.  Inertia and momentum are not forces.
718798
This is too freaky. A problem that goes out of its way to EMPHASIZE weight not mass would give the weight in Newtons. Gram is a unit of mass, not weight.
739302
Probablly the most novel one that I've heard of is in the "lensman" series by EE doc smith, and it involves inertialessness. He had a device that would somehow remove the inertia of the object it was hooked to, thus making it unneccesary to accelerate. I thought this was cool; it had some really interesting ramifications. Good series, too!
733431
Because there is no absolute reference frame for motion, you can only define uniform motion with respect to a specified coordinate frame.\n\nFor example, a ball falling in a vacuum is not in uniform motion with respect to an earth-fixed reference frame; the ball accelerates.\n\nWhen the forces on an obejct sum to zero, that object is in uniform motion with respect to a reference frame that is non-accelerated. That means that if you compare gravity acceleration between the a frame fixed to the object, and the frame you are wondering about, if the gravity is the same, the frames are not accelerated with respect to each other.\n\nOthers have suggested that uniform motion requires absence of forces. This is not quite true - it requires absence of *net* forces. For example, a car traveling a constant velocity on a highway is not in a force-free environment: you can identify forces of air friction, propulsion from the wheels, weight, and support from the pavement. However it is considered to be in uniform motion with respect to a reference frame fixed to the earth, because all of those forces sum to zero, and because the apparent gravity in a frame fixed to the car is the same as in a frame fixed to the earth.
939985
Well, yes, the gavity is pulling you down, and you are not moving. So you are subjected to an acceleration and are not moving.\nMind you, one can argue that the *resulting* force is zero, as the ground is reacting with an equal and opposite force to your weight; if you take it that way, to have an unbalanced force should result in motion.
280629
We would never FEEL it rotate because it acts directly opposite to gravity. The only way we would feel it it if it CHANGED in velocity.
1117792
Let's make this simple: \n\nInertia and Momentum refer to Newton's 1st Law...Momentum tell us that an object in motion will stay in motion, and inertia tell us that an object at rest will stay at rest...both until acted upon by an unbalanced force.\n\nKinectic energy refers to the energy of moving objects.  (as opposed to potential energy, that refers to objects that are not moving, but that could move.)\n\nExamples:  \n\nInertia:  A pencil sitting on my desk will not move until something moves it.  This is a very comforting thought if you stop and think about it.\n\nMomentum:  If I'm riding my bike, I will continue to move until the force of gravity pushing down on me, and friction moving against the tires, and the wind blowing in my face all conspire to stop me.\n\nKinetic energy:  This is the sum total of all the energy spent keeping my bicycle moving...my legs pedaling, gravity pushing me down the hill, then subtract the forces acting against me.\n\nHey, it ain't rocket science...it's easy!
570416
That is not a Physics question.
988087
Gravity does not travel; it is a force that varies depending mostly on the size of the bodies in question.
666644
I don't know how so many people are confusing the first law of motion with the second law of motion. People, she's asked for the second 'theory' of motion, which is to be understood, of course as the second law of motion. Which states that the rate of  change of momentum is directly proportional to the impressed force and takes place in the direction of the force. \n\nThe proof of that cannot be derived from first principles, as it is one of the first principles itself. Of course, for a special case in which the system mass is constant, it does reduce to F = ma, but that is really elementary.
195717
dba_gregg has missed the point that both are same weight\n\nThe moment of Inertia of a hollow sphere  is 1.6 times greater than the solid sphere and so it rolls down slowly.\n\nThe speed of solid sphere will be 1.09 times the speed of hollow sphere.
960356
Say your mon asks you to go do your homework. You have initial reluctance...you wanna start getting up to go do it but then you don't quite stand up. Inertia is reluctance of matter to be transformed from one state to another. A little child hits a ball and the ball resists motion. It won't go. However, a bigger boy hits the ball, and at a certaion point uses enough force to get the ball to begin to move. That forces needed to change the ball from static state to dynamic, is your inertia. Or, think of what you need to do to get your ice-cream just begin to melt??  \n\nIt's a probably a good idea you read, study and understand the subject matter, than finding supplied answers for homework. It defeats the purpose of homework. Goodluck
1011658
Ummmm, I think your talking about Centripetal and Centrifugal force....
775838
Okay so this will pretty much be an explanation from a classical physics type of view so we can talk about gravity as a force.\n\nYou're totally right.. gravitational acceleration is a bit of a different experience than another kind might be such as acceleration from a surface pushing on your feet or a rope pulling you through your hands.  If you were in space falling freely towards a body (planet.. whatever you want.. anything with mass) because of gravity you wouldn't feel any acceleration at all.. even a fancy accelerometer would feel nothing.  \n\nThe simple answer is that if you are accelerated by being pulled on by a rope you're holding (instead of gravity.. so you're at some place in space with so little gravity you can forget it for this experiment) you will feel it because the pull of the rope is transferred through your body as a strain between all your molecules.  They're all hanging on to each other and getting pulled along by each other and your nerves can feel this strain.\n\nIf it's a push then it's pretty similar... you're in space, some place with negligible gravity, in an elevator with a rope pulling it in what you could call the "upwards" direction.. ie your head is pointing in the direction of acceleration.. and you're inside it with the floor of it pushing on your feet.. you can FEEL it! why? because the force starts at your feet and is transferred through all the tissues in your body compressing you and your nerves.. and you feel it.\n\nYou don't feel the gravitational acceleration because it accelerates every single atom in your body exactly the same way.  They all speed up just the same way as each other and there is no force needed between them.\n\nThink about it like this... if you were in the space elevator again and you were actually made of just a bunch of tiny pieces of stuff all unattached to each other... lake say you were made of sand or something all just floating there undisturbed at first... then the elevator started accelerating! what would happen? well you would end up all mushed against the elevator floor in a big pile.. why? because you had no internal structure to keep you stuck together... if you do have this internal structure with your bones and flesh all stuck together, like you do, then they would all be fighting to cling together and not squish together or tear apart and avoid mushing up on the bottom floor.  You're a solid structure.  Those stresses in your tissues are what you feel.. it's the attachment between all your little pieces being pushed on or pulled on in every little bit of you that you can feel.\n\nHope this helps!