| ylbtech- physics - two forces balance: Wikipedia |
Object remains stationary or uniform linear motion under the influence of several forces, then the object is in equilibrium. If the object is in equilibrium under the action of two forces, these two forces are in balance, force balance referred to two.
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- Chinese name: two forces balance
- English name: Balance force
- Nickname: Newton's first law
- Expression: force = counterforce
- Author: Isaac Newton
- Applied science: Physics, Mechanics
- Field of application: Suitable for building respect
- Field of application range: Computational Physics
- Abbreviated equilibrium conditions: ① ② force thereof with the other major force ③ ④ reverse force collinear
table of Contents
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Equilibrium conditions
Size: equal;
Directions: two opposite forces acting on the same object, and in the same line;
Effect: the object remains stationary or moving in either direction made uniform linear motion;
That is: two forces acting on the same object, if equal and opposite directions, and in the same line, these two forces will balance each other.
Two equilibrium conditions are: equal and opposite directions, acting on an object in a straight line, in effect.
Note: two force equilibrium condition is simply the same material, and other large, reverse, collinear. Especially the "same" and "collinear" This condition is often missed beginner, causing incorrect judgment of the two forces balance.
(Note the distinction between a good
balance force
and
interaction
similarities and differences between).
A schematic view of two forces balance
Interaction
1. Same: equal and opposite, and are on the same straight line.
2. Different:
counterweight
: acting on the same object, are two forces.
Interaction force
: acting on different objects, a force, while producing disappears (forces cancel each other).
Two force balance means A → B ← C, while the
interaction
means A / C.
Imbalance force and changes the state of motion of the object
Many examples show that when action by the unbalanced force, its behavior will change objects, some from the static to dynamic and some static to the dynamic, from fast some slow, some fast change from slow, there's original moving object changes direction do
curvilinear motion
.
Two forces acting on an object, if the object can not remain at rest or
uniform motion
states, the two
effects of force
can not cancel each other out (force is not zero), we say that these two forces are unbalanced, also known as non
counterweight
.
note
Motion curve
belongs to
variable motion
, not a two forces balance.
Generalized description
Generalized two forces balance should also include
torque
balance.
If the two forces (or force) is subjected to a force of the object is 0, then it is said to be in equilibrium torque, equilibrium torque at rest or in uniform rotation body (equilibrium state in a broad sense).
Balance force with force comparison:
Similarities: [1] acting on the same object [2] equal size [3] direction opposite to [4] acting in a straight line, may be simply referred to as: the force with the body, strength and so large, the force opposing the force collinear.
Different points: [1] of the imbalance force acting on the same object, the force may be of a different nature;
Interaction force acting on the different objects, the nature of the force is the same
Description:
When the object is determined by whether the two forces of the pair of balance, to see whether the first two forces acting on the same object, and then look at the other three conditions are satisfied at the same time; we can see objects in these two forces or whether to maintain a stationary state under the action of uniform linear motion.
application
(1) by a spring dynamometer suffered gravity measurement object, is the use of two equilibrium conditions.
(2) on the table vase vertically downward by gravity and the desktop of his upward vertical supportive, two forces balance.
(3) hanging chandeliers, vertically downward by gravity and its suspension wire pulling vertically upwards, two forces balance.
(4) uniform linear motion in the horizontal road cars, the traction force in the horizontal direction by the forward and rearward resistance, two forces balance.
(5) in a vertical direction, the car and the road surface by gravity down its upward support force, two forces balance.
(6) When the object is suspended or floating in the liquid (gas), the buoyant force of gravity is equal to, two Solving force balance.
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Objects force conditions
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Object motion
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Explanation
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By counterweight
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Rest or uniform motion |
Forces are not the cause of (maintaining) the movement
|
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By unbalanced force
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Acceleration or deceleration motion |
Force is the reason to change the state of motion of the object
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Experiment: Inquiry Into force equilibrium conditions
Purpose:
1. Experience to explore the two equilibrium conditions of the experiment, induction, summary concluded.
2. By understanding the close relationship between the counterweight and balance relations, to better comprehend the force and movement.
3. By participating in the experiment activities, students actively participate in the initiative mind and spirit of scientific inquiry and the practice of co-operating with each other.
Principle:
Change the state of the object moving force.
experiment equipment:
Car, cotton, hook code, pulleys and so on.
Experimental Procedure:
1. 1, the car on a smooth horizontal table, code to put the hooks attached to both ends of the carriage tray. Thus the tension in the car by two horizontal directions, shown a schematic diagram of two force pulling trolley subjected. Observation car kept in motion invariant under what circumstances.
2. Presses a car, changing the number of codes hook ends of the two tension varying sizes. Then let go, can not observe the car remains stationary.
3. Hand hold the same car, so that the hook ends equal number codes, so that the two directions of force, and then let go, the car can remain stationary observation.
4. Presses a car, so that the hook ends equal number codes, so that a twist angle of the car, and then let go, the car can remain stationary observation.
5. Presses a car, so that the hook ends codes equal number, let the opposite direction of pull and in the same line, and then let go, the car can remain stationary observation.
Analysis and demonstration:
To ensure that the object is in equilibrium, two forces in the same object is effect, must be equal and opposite, and acting on the same straight line. Simply put, it is this: with the body, contour, reverse, collinear.
Assessment:
The experiment also trolley frictional resistance in the horizontal direction, a force in the horizontal direction by the trolley is actually three. If the resistance is much smaller than the two tension can be ignored, it can be considered approximately horizontal direction by the trolley by two tension. This requires that the desktop as smooth as possible; car wheels rolling freely; large selection of quality hook code, so that the two tension as large as possible, in order to weaken the influence of friction. Two trays used have the same
Improved experimental apparatus: may be square with a paper card (note that some good lightweight) was used instead of a body as a car, are represented by two lines passing through the jam and toggled diagonal, the other ends of the bypass line formwork table pulleys is linked code. Then the steps above experiment.
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