The two forces acting on the same point are F1 = 5N and F2 = 4N. If the angle between the resultant force F and F1 is θ, then θ may be () A. 45°B. 60°C. 75°D. 90°

The two forces acting on the same point are F1 = 5N and F2 = 4N. If the angle between the resultant force F and F1 is θ, then θ may be () A. 45°B. 60°C. 75°D. 90°

According to the trigonometric rule, the resultant force F of two forces F1 and F2 is obtained, as shown in the figure. According to the geometric knowledge, when F2 is perpendicular to the resultant force F, θ is the maximum. If the maximum value of θ is θ m, then sin θ M = f2f1 = 45, θ M = 53 °, so θ may be 45 °

When F 1 = 4N, the resultant force of the two forces is just perpendicular to F 1
An object is subjected to two forces F1 and F2. When F1 = 4N, the resultant force of the two forces is just perpendicular to F1. Now the direction of F1 and F2 remains unchanged. When F1 increases to 8N, the resultant force is just perpendicular to F2
(1) The size of F2
(2) The angle between F1 and F2

Let the opposite angle between F2 and F1 be θ
When F1 = 4N, the resultant force of the two forces is just perpendicular to F1
F1 / cos θ = F2, that is 4 / cos θ = F2
When F1 increases to 8N, the resultant force is perpendicular to F2
F2 = f1cos θ, that is 8cos θ = F2
The simultaneous solution is that θ = 45 ° F2 = 2 under the root of 4 *
Therefore, the angle between F1 and F2 is 135 degrees

As shown in the figure, the object m is placed on a horizontal plane and subjected to two horizontal forces, F1 = 4N and F2 = 8N. The object is at rest. If the horizontal force F1 is increased by 5N, then ()
A. Object m is still at rest B. the direction of resultant force on object m is to the left C. the direction of resultant force on object m is to the right D. the friction force on object m is equal to 5 & nbsp; n

When the object is acted by three forces in the horizontal direction, namely F1 = 4N, F2 = 8N and friction force, according to the balance condition, we can know that the static friction force is 4N in the same direction as F1; if the horizontal force F1 is increased by 4N to 9N and the direction is unchanged, F2 = 8N, the resultant force of the two forces is 1n and the direction is the same as F1; according to the balance condition, we can know that the static friction force is 1n in the same direction as F2; Therefore: a

Two objects a and B, with mass M1 and M2 respectively, contact each other on a smooth horizontal plane, and apply a horizontal thrust f to the object, then the force of a on B is
Two objects a and B, with mass M1 and M2 respectively, contact each other on a smooth horizontal plane, and apply a horizontal thrust f to the object, then the force of a on B is
A.F B.(m1*F)/(m1+m2)
C.(m2*F)/(m1+m2) D.m1*F/m2
Try to explain how it works
If we calculate a, then M1 * a = f, and M2 = 0

A and B, as well as AB have the same acceleration, and the equation is: F = (M1 + m2) a, f '= M2A. The result is obtained by dividing the two equations. When choosing C to do this kind of stress analysis, we should flexibly use the methods of overall analysis and individual analysis
If we calculate a, we should use the following formula: f-f '= m1a, because a is subjected to two forces, the whole and B to A. when doing this kind of problem, we should pay attention to drawing the force analysis diagram