How to calculate the average force

1.

1. Gravity g = mg

(vertically downward, g = 9.8m/s2 ≈ 10m / S2, the action point is at the center of gravity, applicable to the earth surface)

2. Hooke's law f = KX

{along the recovery deformation direction, K: stiffness coefficient (n / M), X: deformation variable (m)}

3. Sliding friction force F = μ FN

{opposite to the relative motion direction of the object, μ： Friction coefficient, FN: positive pressure (n)}

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extended data:

different classification of force

1. According to the nature of force, it can be divided into gravity, universal gravitation, elastic force, friction force, molecular force, electromagnetic force, nuclear force, etc Note that gravity is not equal to gravity under all conditions Gravity does not point to the center of the earth under all conditions. Gravity is a component of the earth's gravitational force on an object, and the other component is a centripetal force. Only on the equator does gravity point to the center of the earth.)

According to the effect of force, it can be divided into tension, tension, pressure, supporting force, power, resistance, centripetal force, restoring force, etc

According to the research object, it can be divided into external force and internal force

According to the action mode of force, it can be divided into non-contact force (such as gravitation, electromagnetic force, etc.) and contact force (such as elastic force, friction force, etc.)

There are four basic interactions (forces): gravitational interaction, electromagnetic interaction, strong interaction and weak interaction

nature of force:

materiality: force is the effect of an object (matter, mass) on an object (matter, mass). When an object is subjected to a force, another object must exert this effect on it. Force cannot exist independently without an object

interactivity (interaction): the interaction between any two objects is always mutual, and the object exerting the force must also be the object under the force. As long as one body exerts a force on another, the stressed body in turn will surely add a force to the exerted body Generating conditions: the force is equal in size (the resultant force is zero, in a state of non directional static motion) or not equal, in the opposite direction, acting on two different objects, and acting on the same straight line. It can be summarized as: foreign body, equivalent, reverse, collinear. A pair of interaction forces must proce and disappear at the same time.)

Vectoriality: force is a vector, which has both magnitude and direction

simultaneity: the force proced and disappeared at the same time

independence: the effect of one force does not affect the effect of another

includes three elements: the size, direction and action point of the force. The accurate expression of the three elements of force by a directed line segment is called the diagram of force. The size is represented by the length of a scaled line segment, the direction is represented by an arrow, the point of action is represented by an arrow or the tail of an arrow, and the straight line along which the direction of a force follows is called the line of action of a force. The diagram of the force is used for the calculation of the force. When the judgment power is large, we must pay attention to the scale of the line segment, because even if one line segment is longer than another line segment, but the scale of the long line segment is also longer, the force represented by the short line segment is not necessarily smaller than that represented by the long line segment

2. When f = f (T), v = V (T), the work from T1 to T2 is equal to ∫ [T1 → T2] f (T) · V (T) DT, which is the accumulation of instantaneous power and time. The instantaneous power is the cosine of the angle between the force and the velocity direction, which is fvcos θ When the instantaneous power can conform to a certain law

3. The jumping distance of this person is 0.4 meters, which takes 0.4 seconds, and the average speed is 0.4 / 0.4 = 1 meter / second. Assuming that the bouncing force is constant (this assumption does not affect the result), the bouncing process is uniform acceleration. Final velocity = 2 * 1 = 2m / s
ft = MV
f * 0.4 = 60 * 2
F = 300 cattle. The 300 n is the resultant force of the bouncing force and gravity, so the bouncing force = 60 * 10 + 300 = 900 n. That is, the average force is 900 n
the end of the bounce is the beginning of the upward even deceleration movement. The kinetic energy at the beginning is equal to the potential energy at the highest point: MV & # 178/ 2=mgh
h=v²/ 2g=2²/ 2 * 10) = 0.2m.

4.

The uniform load can be regarded as a concentrated force. The size of the concentrated force is the area of the uniform load (Q · L), which acts on the midpoint (L / 2) of the distribution area

using the formula of uniformly distributed load to calculate bending moment, it can be simply considered that M = (Q * x ^ 2) / 2, X is the length of uniformly distributed load. Its origin is: Q * x is the resultant force F acting on the structure, the unit is n, the action point of resultant force is located at the midpoint of load action, so the arm of force of F is x / 2m, so the bending moment M = (Q * x ^ 2) / 2

In physics, torque refers to the tendency that the force makes the object rotate around the axis of rotation or fulcrum. The unit of moment is Newton meter. The Greek letter is tau

The concept of

moment originated from Archimedes' research on lever. Rotational torque is also called torque or torque. Torque can change the rotational motion of an object. Pushing or pulling involves forces, while torsion involves moments. The moment is equal to the cross proct of the radial vector and the applied force

extended data:

Properties of moment:

1. The moment of force F to point O is not only determined by the force, but also related to the position of moment center. The moment varies with the position of the moment center

When the force is zero or the arm of force is zero, the moment is zero

When the force moves along its action line, because the magnitude, direction and arm of the force do not change, the moment does not change

The algebraic sum of the moments of two mutually balanced forces at the same point is equal to zero

5. The average force can be used when the force is uniform, but it cannot be used in other cases. The average force = (minimum force + maximum force) divided by 2

6. The point of action of the force is set at half of the length of the uniform distribution of the force, and then it can be calculated as a resultant force. The point of action is the midpoint

7. The point of action of the force is set at half of the length of the uniform distribution of the force, and then it can be calculated as a resultant force. The point of action is the midpoint

8. The area below the line is impulse, f is 2n, and the mass of the object remains unchanged, then it makes a uniform speed straight line (friction is 2n) with uniform acceleration and linear motion with acceleration

9. The total work is based on the number of people