Know how to calculate friction by weight and tension

1. The pulling force acting on the same object is not necessarily related to the friction force unless the acceleration of the object is known

2. It will take us about twenty minutes to get to the sports center

3. Look at the moving state of an object
if it is in a uniform linear motion or static state, then the friction is equal to the pulling force
if it is not in a uniform linear motion or static state, then it should be considered in combination with the dynamic friction coefficient

4. Child, friction is not created out of thin air. It doesn't mean that as long as an object has friction. For example, if you stand on a level ground, there will be no friction. Friction refers to the force that hinders the relative motion of two objects when they are in relative motion or have the trend of relative motion. It is not a single object, but the force between two objects. For example, when using the rubber, there is friction between the rubber and the paper. If you push a big stone in the horizontal direction, but you don't push it, that's the friction against you. The friction force is related to the pressure and roughness of the contact surface, but not to the gravity
friction factor refers to the ratio of the friction between two surfaces to the vertical force acting on one surface. It is related to the surface roughness, but has nothing to do with the size of the contact area. According to the nature of motion, it can be divided into dynamic friction coefficient and static friction coefficient
I wish you progress in your study!!

5. If the object moves in a straight line at a constant speed on a horizontal plane, the pulling force is horizontal, and there is no third force in the horizontal direction, the friction is equal to the pulling force. If the object slides down at a constant speed on a vertical plane, and there is no third force in the vertical direction, the friction is equal to gravity

6. Since there is no way to illustrate it with a graph, let's simplify the problem. Suppose that the object is on a horizontal plane, and the friction factor between it and the horizontal plane is μ, He received an angle of 0 θ The force F just makes it move at a uniform speed, so the pressure of the object on the horizontal plane is mg fsin θ, So the friction is zero μ mg-Fsin θ, If the horizontal component of F is just equal to the friction force, then there is fcos θ=μ mg-Fsin θ, Fcos after item transfer θ = μ mg- μ Fsin θ, So F= μ mg/cos θ+μ sin θ. In order to minimize F, we must let (COS θ+μ sin θ Maximum.
let sin α=μ/ Radical μ&# 178;+ 1) , then cos θ+μ sin θ= sin( α+θ), The maximum value is 1 θ= ninety °-α
back to this topic, if the slope of the system can be horizontal, then it can be regarded as the friction factor μ sin θ The above system, and then the same way to solve it, at this time the calculated angle is also the angle after transformation, if you want to calculate the real angle θ It's just a degree

7. According to the motion of the object to determine the acceleration, and then use Newton's second law to determine the force on the object.

8. W useful = TS matter = (g matter - f floating) s matter

9. What kind of sport is it. Constant speed or constant acceleration. At a constant speed, the pull is equal to the friction. If there is acceleration, it is tension minus friction, which is equal to the proct of mass and acceleration.