The physics of tug of war kneel and beg! Explanation of the physical phenomenon of tug of war

The tug-of-war competition uses the three physical concepts of "positive pressure", "friction" and "moment".

In the tug-of-war, let's first analyze several situations that determine the outcome of the war:

1. The losing team was pulled to its feet, and then pounced forward;

2. The losing team was pulled "as it was";

3. The comprehensive situation of the above two situations.

The first case: because the moment with the foot as the pivot point is small, under the pull of the opponent, the person is pulled to "turn", so the foot is forced to move forward, and finally loses the game.

In the second case, it is because the friction between the foot and the ground is not strong enough, resulting in being pulled "untouched" - the foot rubbing the ground - and finally losing the game.

The third case: Based on the analysis of the above two situations, it is not difficult to draw conclusions.

In tug-of-war, the athlete always maintains a reclining posture – maximizing the friction from the ground into a pull on the rope.

As a force, there is no doubt that it comes from the weight of the athlete and the coefficient of friction between the sole and the ground. But that's just the premise. It is necessary to translate this premise into a pull on the rope in order to win. Here's the trick: how to maximize that conversion!

In order not to allow the opposing athlete to pull and "turn", he must have an opposite moment - maintain a reclining position - to increase the difficulty of being pulled and "turned". But in this way, the positive pressure of the body weight on the ground will be reduced, increasing the likelihood of being pulled "as it is".

In the case of a close match, the principles of adjusting posture are as follows:

1. When the friction on the ground is sufficient, but it has been perceived that there is a possibility of being pulled and "turned", the rope can be slightly longer, or the footsteps can be moved forward slightly, so that it has a more oblique slope - increase the torque - to achieve the purpose of increasing the force on the rope.

2. When the person is not pulled up, but the footsteps have a tendency to slide, you can retract the rope a little - adjust the slope a little less - increase the positive pressure of the body weight on the ground, thereby increasing the friction. Or take advantage of uneven terrain to increase friction.

3. When you confirm that your teammate's weight is greater than that of the opposing team, you can also use the force together under the command of the team leader - the rope tension acts on the athletes of both teams at the same time - the possibility of the opposing athlete being pulled and "turned" will increase, and it may also make the opponent "mess up".

In short, choose athletes with a lot of weight, choose shoes with a high coefficient of friction, and pre-wrap something (or knot) around the rope to prevent your hands from slipping.

Friction, the rougher the contact surface, the greater the friction, that is, the easier it is to win

Gravity and kinetic friction factors determine friction and have nothing to do with hand grip or pull.

It is the interaction of forces. Hope!

Physics is a natural science, and physical knowledge is the best for the society and serves the society. Many phenomena in life can be explained with physical knowledge and unveil its mystery, which is illustrated by a few examples.

1. Is the tug-of-war just a matter of strength?

What is a tug-of-war competition for? Many people will say: Of course, it is stronger than which team!

Actually, the question is not that simple. According to Newton's third law (i.e., when object A gives a force to object B, object B must simultaneously give object A a a reaction force of equal size, opposite direction, and in the same straight line), how much pull force A exerts on B for the two teams of tug-of-war, and B also produces the same amount of pull force on A at the same time. It can be seen that the pull between the two sides is not the factor that determines the victory or defeat.

A force analysis of the two teams in the tug-of-war shows that as long as the tensile force is less than the maximum static friction with the ground, it will not be pulled. Therefore, increasing the friction with the ground becomes the key to victory or defeat. First of all, wearing shoes with concave and convex soles can increase the coefficient of friction and increase the friction force; In addition, the heavier the weight of the players, the greater the pressure on the ground, and the greater the friction.

When it comes to tug-of-war between adults and children, adults easily win, and the key is that adults weigh more than children.

Also, in a tug-of-war, winning or losing depends a lot on people's skills. For example, if you push the ground, you can put more pressure on the ground than you think about in a short period of time. Another example is when a person leans back, using the pull of the other party to increase the pressure on the ground, and so on.

The aim is to maximize the friction on the soles of the feet in order to win the game.

It doesn't matter how much force you exert in tug-of-war, for the two teams in tug-of-war, how much pull A exerts on B, and B also produces the same amount of pull on A at the same time. The key to the victory or defeat of the tug-of-war lies in the maximum filial piety and the high prudence of the friction, and the greater the maximum static friction, the greater the certainty of victory. And the maximum static friction force is large, depending on the mass of the object, so the tug-of-war is best attended by people with large mass.

The tension of the rope is fixed, the force of the person pulling the rope is different, you see the rope as a spring, the force of the person on the left pulling the rope may be 10n, the pulling force of the rope may be 5n, the force of the person on the right pulling the rope may be 8n, and the same force you said is the force of the rope, the pull force of the rope to the person on the left is 5n, and the pull force to the person on the right is 5n, as for the movement of the rope, don't simply divide the rope, when you use the rope to pull the wooden block, the rope is just the transmission of your force, if the person pulls two ropes on both sides, And there is a wooden block tied between the two ropes, if the two pull different forces, the object will not move, which is also the reason why the rope moves every point.

You confuse the concept of action reaction force with equilibrium force: the action force reaction force is for the force object and the force object, A exerts a force of 5n on B, then B reacts to A is also 5N, note that the force object and the force object before and after are just reversed; If the object is subjected to two tensile forces in the left and right directions of 5n each, then the object is subjected to a pair of balanced forces, and the stressed object is the same;

How do you know that the people at both ends of the rope must have equal tension on the rope? If it is equal, the force balance of the rope will not move, but when the force of one side is larger, for the rope, the force of 2 a large point and the force of a small point is not 0, of course, it moves to the side with more strength;

The pull force is equal, of course, do not move, the key is that when the tug-of-war, the pull of the rope on both sides may not be equal.

It's all about friction. The force of the rope is a pair of balanced forces, but the friction of the players' feet to the ground is different, and whichever side has the most friction will win, which is why the tug-of-war competition has to switch venues. Friction is directly proportional to positive pressure, and the heavier side is likely to win.

6 000 n 5 500 n

Analysis The students on both sides are "stalemate", implying that the students on both sides are in a state of static equilibrium First, taking "all the students of Party A" as the research object, "the total friction force between the ground and all the team members of Party A is 6 000 N", and the tension on the rope at A is judged to be 6 000 N according to the balance of the two forces. In the same way, taking "all the students of Party B" as the research object, the total friction force of all team members of Party B is determined to be 6 000 N.

The tension on the rope at A is 6 000 N, and the horizontal tension of the pair of ropes at B1 is 500 N, then the tension on the rope at B is 5 500 N.

Since the interaction forces are equal, only the rope needs to be considered, is the force of A on the rope and the force of B on the rope equal?

Generally, the rope moves slowly during tug-of-war, so it can be seen as a state of equilibrium, which is equal at this time;

If the condition is that the force used by A is always greater than the force used by B, then the force of the rope to A is greater than the force of the rope to B, which means that the rope will accelerate. The key depends on what you mean by F A and F B?

The force given by the rope is equal and it is the frictional force that makes it win.