An object is subjected to three forces in the same plane at the same time. Among the following groups of forces, their resultant force can not be zero () A. 5N 　7N 　8 NB. 2N 　 3N 　 5NC. 1N 　 5N 　 10 ND. 1N 　 10N 　 10N

When the resultant force of three forces is 0, the resultant force of any two forces is equal to that of the third force, and the direction is opposite. Therefore, any one force is in the resultant force range of the other two forces. The resultant force range of a, 5N and 7n is 2n-12n, 8N is in the resultant force range, so the resultant force of three forces may be 0

How to draw the resultant force of three forces

First draw the resultant force of any two forces, and then draw the resultant force of the resultant force and the third force!

There are two forces, one is 10N and the other is 2n. Their resultant energy is 5n.10n.15n
There are two forces, one is 10N and the other is 2n. Their resultant energy is 5n.10n.15n
reason!

Consider the limit case
Same direction: 10 + 2 = 12
Reverse: 10-2 = 8
The possible values are between 8 and 12, so 10N is possible and the others are impossible

A force of 10N can be decomposed into two coplanar forces of 5N and 4N
A 10N force can be decomposed into two 10N forces

In the synthesis and decomposition of forces, the two forces to be synthesized (or decomposed) are made into parallelogram, and the diagonal of parallelogram is made from the starting point of the force, then the diagonal is the resultant force or the force to be decomposed

The three-point force is 2 N, 3 N and 4 N respectively, and the resultant force of the three-point force is the smallest and the largest

When the three forces are in the same direction, the resultant force is the largest, which is 9N
Since 2n + 3N ＞ 4N, the resultant force may be 4N, and it can be opposite to the direction of 4N, so the minimum can be 0

There are three common forces on the plane, which are 2n, 7n and 10N respectively

1——19N

Finding the resultant force according to the rule of parallelogram
The parallelogram rule says that the diagonal length of a parallelogram is a resultant force! But a parallelogram has two diagonal lines! The length is different! Which one should be taken?

Take the one from the starting point of the two forces

How to calculate the resultant force through two components when using parallelogram rule
There are often questions to calculate the resultant force. I always use f = root sign F1 & # 178; + F2 & # 178; + 2f1f2cos α, which is very troublesome. Sometimes I don't know the angle

For the general case, it is very simple to use the formula F 1 & # 178; + F 2 & # 178; + 2F 1F 2cos α to calculate. If it is a specific topic, it can also be said that a special case, in order to find the corresponding simple method
If sometimes the angle is not known, there is no simple general method

How to explain the parallelogram rule in physics?

When two forces are combined, take the line segment representing the two forces as the adjacent side to make a parallelogram, and the diagonal line between the two adjacent sides represents the size and direction of the resultant force

How to use parallelogram rule to find resultant force
For example, the two components are 3.2 and 2.6 n

A force is a vector. You can't do it only by its size. You also need to know the direction of the force. In a parallelogram, it is the angle between 3.2 and 2.6. Then make a parallelogram. The diagonal is the resultant force. The diagonal is the diagonal starting from the intersection of two forces

An object is subjected to three forces in the same plane at the same time. Among the following groups of forces, their resultant force can not be zero () A. 5N 7N 8 NB. 2N 3N 5NC. 1N 5N 10 ND. 1N 10N 10N