The three co force points, which are 2N 7N 8N, are the maximum and minimum values of their resultant

If all three forces are in the same line and in the same direction, the maximum force f = 2 + 7 + 8 = 17n is generated

But if the force of 2n and 7n produces the resultant force of exactly 8n (5n 2n + 7n 9n).

And in the opposite direction of another force of 8n, then the three forces can cancel each other out, resulting in a minimum force of 0n

The maximum net force is 2n + 7n + 8n = 17n

The minimum is 0n, which is well explained by the triangle rule.

2, 7, and 8 can form a closed triangle, so the minimum net force is 0

Obviously, they act in the same direction at the same point with a maximum force of 17

17 and 0 2 and 7 have a resultant force range of (1,9), and the third force 8 is within this range, so the resultant force of 2 and 7 must have one that can be canceled out by 8.

First find the range of the resultant force of any one or two, and then the third force will find the resultant force with this resultant force, of course, take the opposite force of the third force to make the three forces the resultant force minimum. I don't know if you understand?

You can think of it this way, the maximum resultant force of 2 and 7 is 9, and the minimum is 5, right?? So that means that 2 and 7 must have a resultant force of 8, so that the force with 8n can be combined

The maximum value is, of course, theirs and seventeen, and the minimum value is determined by the triangle rule of the force, and they can be three sides of the triangle so it is zero.

When the three forces are in the same direction, the resultant force is the largest, which is: 3+4+5=12nThe resultant force range of the first two forces is: 1n (opposite direction) and 7n (same direction), which is a certain angle between 1 and 7.

Synthesis of forces. The third force is 5n, and 5 is between 1 and 7, so make the net force of the first two forces 5, and then make the force of 5n in the opposite direction of this resultant force, you can synthesize a force of 0n.

Oh oh, when the negligence caused the error, sorry, it is now modified as follows:

The magnitude of the three common point forces is 5n, 3n, and 7n respectively, then the minimum value of their resultant force is (0n) Description: When the three forces are in the same straight line and the direction is the same, the maximum value is obtained: f resultant force = 5 + 3 + 7 = 15n;

The three forces are not in the same straight line, that is, when the direction is not the same, the force of 7n is fixed, and the force of 5n and 3n is taken at the appropriate angle to form a force of 7n. And in the opposite direction of the original force of 7n, the minimum value is obtained: f resultant force = 7-7 = 0n

The simple way to determine whether the forces of 5n and 3n can be combined into the force of 7n is to take 7 as the three sides of a triangle, and if this triangle exists, it can be synthesized; If it doesn't exist, it can't be crafted. According to the three sides, the method of determining whether a triangle exists:

That is, the family grip is judged by the fact that the sum of any two sides is greater than the third side, and the absolute value of the difference between any two sides is less than the third side.

Collinear, co-directional, the maximum value of the resultant force = 2 + 7 + 8 = 17n2n and 7n The range of the net force of these two forces is: less than or equal to 9n, greater than or equal to 5n, so the net force of these two forces can be equal to the third force 8n, as long as the direction is opposite to the third force, the net force is zero.

So the minimum value is zero.

When the three forces are in the same direction, the net force has a maximum value, and the resultant force range of f=2+3+8=13(n)2n, 3n is: 1n to 5n, and there is no case where the net force in the opposite direction of 8n is 0.

The resultant force range of 2N and 8N is: 6N to 10N, including 8N, if it is reversed with the third force 8N. The resultant force of these three forces is 0

The resultant force range of 3n and 8n is: 5n to 11n, and there is no case where the net force in the opposite direction of 2n is 0 (the resultant force range with two of these forces includes the third force, and the rest should not be discussed again, so the resultant force range of 2n and 5n should not be discussed again).

This is how these kinds of questions are thought about and answered.

The maximum value of the resultant force = 2 + 7 + 8 = 17n

The minimum values are 0, 2n and 7n, and the net force ranges from 5n to 9n, where there is 8n, and if this 8n is exactly the opposite of 8n in the problem, then the net force is 0

The maximum net force is 8+2+3=13n in the same direction of the colline, and the minimum is 8n-(2n+3n)=3n

Analysis: When the direction of these three forces is the same, the total resultant force has a maximum value, so the maximum value of the resultant force is f1 f2 f3 (magnitude added) 5 7 10 22 N When the minimum value of the resultant force of these three forces is required, the following method can be used:

1. Combine the two forces first to get the range where their resultant forces are located.

2. Within the above range, take a value closest to the third force, then the difference between this value and the third force is the minimum value of the total resultant force (referring to the magnitude).

According to the above method, for example, the two forces of 5n and 7n are combined first, and the resultant force range is in the closed range of 2n to 12n.

Obviously, in this closed interval, the value closest to the third force (10n) is 10n, so the difference between the two 10n is equal to 0, i.e., the minimum of the resultant force of the three forces is 0.

Note: The maximum or minimum value of the resultant force refers to the magnitude of the resultant force.

The maximum is 22n and the minimum is minus 22n. Because force has direction.

To give you the easiest and easiest way to understand:

When these 4 forces are in the same direction, the total resultant force is the largest, and the maximum value is 2 5 8 20 35n Divide these 4 forces into two groups (2n, 5n) and (8n.). 20n）。

2n, 5n) The net force of these two forces is in the range [3n, 7n].

8n.20n) The net force values of these two forces are in the range [12n, 28n].

Obviously, there is no common area for the resultant values of these two sets of forces, so when the resultant values of these two groups of forces are taken as the closest values, i.e., 7n and 12n, the difference between them is the smallest total resultant force. So, the minimum value of the resultant force of the 4 forces in this problem is 12 7 5n.

Maximum: Maximum when the four forces are in the same direction, net force: 2n + 5n + 8n + 20n 35n

Minimum: When the three smallest forces are in the same direction and are reversed to the maximum force, the net force is minimal: 20n-(2n+5n+8n) 5n

The maximum value is: 35N

The minimum value is: 5n

15n 0

The maximum value of their resultant force.

fmax =(2+3+4+6)n=15n。Because fm = 6n<(2+3+4)n, their net force minimum is 0.

The maximum value is 24n, and the minimum value is 0.

The maximum value is not suspenseful, and when it is in the same direction, it is directly added = 6 + 8 + 10 = 24n.

The fastest way to judge whether the minimum value can be 0 (i.e., completely cancel) is to see if the magnitude of these three forces can form a triangle, using the principle of "the sum of the two sides is greater than the third side". 6+8 10, which means that these three forces can form a triangle, so the forces can be completely canceled out.

Note 2: If the sum of the two sides is less than or equal to the third side, it cannot form a triangle, a+b c, then the minimum value of the net force at this time is fmin=c-b-a, which is obvious, abc is on the same straight line, ab is in the same direction and opposite to c.