2007-11-23 18:05:02 · 7 answers · asked by macon 1 in Science & Mathematics ➔ Physics
To the contrary; when an object of mass m is not moving, the forces on it are in balance so that there is a net force f = 0 = ma; where a = 0 is the acceleration of the mass/object. For example, you weigh W and are standing still. That W is a force, the force of gravity in fact. So you are standing still even thought there is a least one force on you we've already identified.
So if gravity is acting on you, why are you not falling through the floor? Easy, because the floor you're standing on is pushing back with a force F. Thus, f = W - F = 0 = ma and you are not accelerating (a = 0) downward through the floor.
In fact, you're not moving at all because you started standing still and there is no net force to accelerate you from standing still. And even though you're standing still there are two forces acting on you: W and F.
What may be more interesting is that you could be moving and still have no net force f acting on you. Notice that f = W - F = ma = 0 does not say a lick about your current velocity v. So, if you are standing still on a frictionless wagon that is carrying you at a velocity v = constant, f = W - F = 0 = ma is still true. That is, you are still not falling through the wagon because it's pushing back up with a force F = W.
Bottom line, when f <> 0, then a <> 0; so there will be motion...accelerating motion in fact. But when f = 0 an object could be dead still or moving with a constant velocity v = constant. Either way, the net force would be zero even though there are forces acting on the object.
2007-11-23 19:43:31 · answer #1 · answered by oldprof 7 · 0⤊ 0⤋
No not always. Many a times when an object is at rest it still has many forces acting on it. For example when if you and your Friend have a fight on a box (its just an example don't take it seriously) and she tries to pull it away and you resist. The tiffin would be on rest but you both are pulling the box so force is being applied by you both. The force you both apply are opposite in direction. When you go to higher class (I assume that you study in 8th or 9th grade) you will study the addition of vectors. Well for now I would just tell you that when a body is at rest it only means that it is in equilibrium. Because When a object is kept in a table even then it has two forces acting on it, one the force of gravitational force and the other the normal force exerted by the table.
I hope I helped you.
2007-11-23 19:52:23 · answer #2 · answered by Vaibhav Dwivedi 4 · 0⤊ 0⤋
When objects doesn't not move when it is under balanced force .
The object was at rest and two forces of equal magnitude acting opposite to each other . so the resultant force acting on it is equal to zero but there forces that has acting on it .
You determine the motion of an object by the resultant force acting on the object using newtons second law F=ma
2007-11-23 18:14:27 · answer #3 · answered by Murtaza 6 · 0⤊ 0⤋
This is false.
If an object is momentarily stationary, it does not constrain the object's force whatsoever.
If an object is stationary for a finite time, it must have zero net force acting on it. This means that the sum of all forces on it must total zero, but it can still have multiple nonzero forces acting on it.
Famous riddle:
You are standing in the middle of a field with nothing to see for miles around. You take a ball and throw it as hard as you can away from you. The ball flys away but then comes straight back to you. The ball is not attatched to anything and it didn't bounce off anything. How did it come back to you?
2007-11-23 18:14:15 · answer #4 · answered by MooseBoys 6 · 0⤊ 1⤋
Newton’s Third Law of Motion says that every action has an equal and opposite reaction.
Pushing means acting with force on the wall and, according to Newton’s Third Law of Motion, the wall exerts a force on the pushing body. This force is called a reaction. Both forces, the one of action and of reaction are equal in magnitude and oppositely directed. The stronger we push, the stronger the reaction is, so the resultant force is equal ZERO and there is no acceleration or deceleration neither of the body pushing the wall nor of the wall.
2007-11-23 18:20:52 · answer #5 · answered by saq428 6 · 0⤊ 0⤋
nope, when you apply a force but the object did not move, it just means that the force you apply to move the object is similar to the amount of force that is opposing your force. Therefore, your object does not move.
2007-11-23 18:22:11 · answer #6 · answered by hkh 2 · 0⤊ 0⤋
NO...
it merely means that the forces acting on the object are at equilibrium..
besides Gravity always acts on objects...
2007-11-23 18:08:53 · answer #7 · answered by sayamiam 6 · 1⤊ 0⤋