The forces are in opposing directions. For example, a car moving on a freeway at
a constant speed applying a certain force forward has a net force of zero because
the force of air friction is equal to the forward force. If the car was accelerating or
braking, the net force would not be zero. Another example: for an object in free
fall at terminal velocity (not accelerating), the force of gravity downwards equals
the force of air resistance upwards. The two forces cancel out and the result is
an even zero.
Another example, easier to grasp . . .
A collegiate tug-of-war. Several members of the football team pulling one end of
the rope north, and the entire Cheerleading squad pulling the other end of the
rope south. The little hankie dangling from the center of the rope is not moving
at all, because the north force and the south force are exactly equal and they
add up to zero. The net external force on the rope is zero, and although there's
some killer tension in it, the rope as a whole remains at rest.
An object at rest, or an object with a constant velocity are the two possible states of an object with zero net force. An object with zero acceleration has zero net force. There many be several forces acting on the object, such as the force of gravity and the normal force of the ground. Even though an object sitting on the ground has two forces acting on it (gravity, and the normal force) the object does not accelerate because these forces are equal and opposite. An object with zero net force has all forces acting on it equally balanced and cancelling out
The net force that is acting on an object that is not changing speed is centripetal force that is pulling the object into a circular path. However, just to be clear on this point, while the object's "speed" is not changing, it's "velocity" certainly is, because velocity, unlike speed, has a directional component to it.
The speed of an object depends on many things, such as the force that accelerated it, the forces now acting on it, and the object's current speed and mass themselves.
There is no limit as to how many forces can act on an object.
Gravity continues to pull down on it, and the ground will exert an equal and opposite force in the opposite direction to keep it up, but otherwise if an object is still then it either has no force acting on it or any forces on it aren't enough to overcome friction.
An object at rest, or an object with a constant velocity are the two possible states of an object with zero net force. An object with zero acceleration has zero net force. There many be several forces acting on the object, such as the force of gravity and the normal force of the ground. Even though an object sitting on the ground has two forces acting on it (gravity, and the normal force) the object does not accelerate because these forces are equal and opposite. An object with zero net force has all forces acting on it equally balanced and cancelling out
The net force that is acting on an object that is not changing speed is centripetal force that is pulling the object into a circular path. However, just to be clear on this point, while the object's "speed" is not changing, it's "velocity" certainly is, because velocity, unlike speed, has a directional component to it.
The speed of an object depends on many things, such as the force that accelerated it, the forces now acting on it, and the object's current speed and mass themselves.
Forces act by means of exchange particles. There are four basic forces (which operate in numerous different ways) each having its own exchange particle. The force of gravity is conveyed by the graviton. The electromagnetic force is conveyed by the photon. The two nuclear forces are conveyed by mesons. A particle that is exerting a force will emit an exchange particle, and a particle which is experiencing a force will absorb that exchange particle. That is essentially how it works, on a subatomic level. There are also mathematical equations which describe the forces, for example, the electromagnetic force is described by Coulomb's Law.
There is no limit as to how many forces can act on an object.
Gravity continues to pull down on it, and the ground will exert an equal and opposite force in the opposite direction to keep it up, but otherwise if an object is still then it either has no force acting on it or any forces on it aren't enough to overcome friction.
You and I stand on opposite ends of a small car.You are in the back, pushing it forward with a force of 100 pounds. I am in the front, pushing it backward with a force of 100 pounds.I don't know what the "force" on the car is. Is it 200 pounds, 100 each from you and me ? Do we also have to add in the weight of the car ... another 2,000 pounds of gravity pushing it downward ? How about the reaction force of the pavement ... another 2,000 pounds pushing it upward ? I don't know.But I do know the net force on the car ... it's zero. The two horizontal forces on it cancel each other, because they're directed in opposite directions. Same for the vertical forces. Which is why the car doesn't accelerate in any direction ... because the net force in that direction is zero.
In most cases, when a body is at rest, there are two forces acting on it: the force of gravity pulling downward and the normal force pushing upward. These forces are equal and opposite, resulting in a balanced or net force of zero.
However many there are exerted on the object. Usually there is gravity, friction, and another force exerted on the object.
because otherwise there are too many variables to upset the calculation of forces and the data wont be accurate. If you know the direction then its many less variables to consider.
There are many forces acting on a body. But, the moves because of the net force acting on it. So, we can say that the body accelerates because of net force acting on it only.
There are two forces acting on a water rocket. The thrust which the force that is given to the water rocket to make it move, and the other one is the gravity.