A question in physics about the balance of two forces

cThere are 4 conditions for equilibrium. That is, the same thing (the same object) and the same line (the same straight line) are equal in size (the same size in the middle) and opposite (opposite directions). It can be seen from this.

A: The support force of the ground facing the athlete = the gravity of the athlete The gravity of the barbell.

B: The gravitational force object of the barbell is the barbell, and the pressure on the athlete The force object is the athlete.

C: The force of the athlete on the barbell and the gravitational force of the barbell The stressed objects are all barbells, which are in the same straight line (vertical), the same size (because they stay in the air), and in opposite directions (one vertically up, one vertically down).

D: See Alz, you have to choose me, I worked hard.

Choose CA: The supporting force is greater than the athlete's gravity.

b: The stressed object is different.

D: Same as A?

ca, without the addition of a barbell.

b, the gravity of the barbell is the same force as the pressure on the athlete, not the balance force.

d, without the addition of a barbell.

c Because the force of the athlete on the barbell and the force of gravity on the barbell are both barbells.

You remember: the equilibrium force must be two forces acting on the same object and the forces are equal in magnitude and opposite directions.

Here Ad does not satisfy a pair of equal forces, B does not satisfy acting on the same object, only C is right.

Answer: The equilibrium force acts on the same object!

A false. Although it is on the same object, the athlete's gravitational force is less than the ground supporting him, so it is unbalanced.

B false, the gravity of the barbell acts on the barbell, and the pressure on the athlete acts on the athlete.

c Pair. All act on the barbell and are balanced.

D false. Same as a.

c. Because the barbell is in equilibrium, it accepts balance and it receives only two forces, so these two forces are balanced by all means.

If an object can remain at rest or move in a straight line at a uniform speed when it is subjected to two forces, we say that the object is in equilibrium.

Two forces acting on the same object at the same time on the same straight line, if the object remains at rest or in a uniform linear motion, then the effect of these two forces on the motion of the object cancels each other out (the net force is 0), we say that the two forces are balanced.

Conditions for the balance of two forces:

Size: Equal.

Direction: Opposite (and on the same line).

Two forces act on the same object.

Effect: The object remains stationary or moves in a straight line in either direction.

Two forces acting on the same object, if they are equal in magnitude, opposite in direction, and on the same straight line, the two forces balance each other.

Note: The conditions for the equilibrium of two forces are simply homogeneous, equal, inverted, and collinear.

In particular, the conditions of "homogeneity" and "collinearity" are often missed by beginners, resulting in incorrect judgments about the balance of the two forces. (Be careful to distinguish between the similarities and differences between the equilibrium force and the interaction force).

In the movie "Captain America 2", the director of S.H.I.E.L.D. is hunted and killed by the Hydra organization. Nick drives a car that resembles a tank and goes all the way. Bucky dropped a bomb under the chassis of the car, and the bomb**, the car's uniform speed and straight driving state were instantly subverted.

So how can you keep an object moving in a straight line at a uniform speed?

Figure 1: Gravity g and the support force f given by the ground

Figure 2, the tensile force given by gravity g and the wire.

The first is the gravitational force of the object and the support force of the ground towards the object.

(1) When the card is stationary, he finds that the pull lines are not on the same straight line (as shown in Figure A), so he concludes: when the two forces are balanced, the two forces can not be on the same straight line, and you think the reason for this situation is.

Cards have gravity.

To get a scientific conclusion, please give him a suggestion for improvement:

I choose a lightweight card.

2) Whether the balance of two forces is related to the magnitude of the two forces.

(1) The gravity of the card is too large, and lightweight paper is used.

2) When the two forces are in balance, whether the magnitude of the two forces is equal.

(1) The raindrops start falling for a period of time to do an acceleration motion.

2) In the process of raindrops falling, when the air resistance increases to equal to the gravitational force of the raindrops, it will not increase again, and the force of the raindrops should meet the conditions of equilibrium force, and the two forces are equal in magnitude and opposite in direction, and the raindrops will move at a uniform speed.

Physical wolf pack.

(1) Acceleration.

2) Acceleration; equal to gravity; two-force balance; Uniform.

The process of Cho Chang see the figure Shen Wu piece tour this or.

mgsin30°=mg cos30° chiropractic spring =3 3

mgsin60°-fcos60°=(mgcos60°+fsin60°) where m=2kg; g=10n/kg; μ3/3

Solve the cherry hand resistance f=20 3 potato mu 3n=

Answer: The answer should be: B

Because of the explanation, after the balloon leaves the ground, it rises in a straight line at a constant speed of 1 m s. It didn't accelerate. That is to say, the net force that the balloon loves is zero (the air force is equal to 5500N).Continue to rise at the same average rate as before.

Answer: aThe air force is less than 5500N, and the direction is downward, and the conclusion is correct regardless of the topic. But with this question to explain:"After leaving the ground, it rises in a straight line at a constant speed of 1m s"The title does not match. Therefore, answer A is inappropriate.

b Do the question must be clear about the meaning of the question, the question is very clear that ten uniform speed straight up, that is, the resultant force is zero!! And the hot air balloon is only subject to the force of the air and gravity, and the gravity is straight down, and the force of the air is naturally straight up!!

The air actually has vertical downward resistance to the balloon, and because the hot air balloon is heating, it is subjected to an upward force, but the resultant force of the air is balanced with gravity!!

Rising at a constant speed, the balloon is subjected to the balancing force, which is equal in magnitude and opposite in direction. So it's b

Isn't lift the force of air?

Equipoise doesn't have to come in pairs. Maybe three, four, five, or even more. The balance is unbalanced, depending on whether these forces can be canceled out by the parallelogram rule.

If it is true that it can be offset to zero, then these forces are considered to be in equilibrium, otherwise they are not balanced.

Your understanding is so confusing.

If the force is unbalanced, we don't talk about the unbalanced force. (Note that this claim does not exist.) ）

Moreover, when the object is balanced by forces, these forces that can be balanced have no necessary logical relationship except that the stressed objects are the same (pay attention to the difference between the interaction forces, which appear at the same time and disappear at the same time, equal in size and in reverse. acts on two objects, whereas the equilibrium force acts on the same object).

You're talking so messy. A force was proposed by Newton, and when two forces are equal to a large reverse collinear, it is called a balanced force (acting on the same object). When an object collects multiple forces, when a pair of equilibrium forces are unbalanced, it will be affected by the force and move.

The net force of all the forces experienced by the object is not 0