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The object with mass m is stationary on the horizontal desktop, and the dynamic friction coefficient between the object and the desktop is μ， Now push the object with a horizontal force to accelerate the object for a period of time. Remove the force, and the object will slide for a period of time and then stand still. Given that the total distance of the object is s, what is the work done by this thrust to the object?
For the whole process, from the kinetic energy theorem:
W- μ mgs=0
Then the work done by this thrust on the object is: W= μ mgs
A: the work done by this thrust on the object is μ mgs．
A long board with a mass of M and a length of L is placed on the horizontal desktop. A small board with a mass of M and a length of negligible is placed at the right end of the board. The dynamic friction factor between the small board and the board and between the board and the desktop is u. at the beginning, the small board and the board are stationary. From a certain time, a tensile force with a constant size of F and a horizontal right direction is applied to the board. If the maximum friction force is equal to the sliding friction force, find (1) To pull the long board out of the small board, pull f to meet the conditions (2) If the tensile force F = 5u (M + m) g, calculate the time from the start of movement to the pull-down of the board from the small board
1. The condition for pulling out is that the acceleration of short board A1 ＜ the acceleration of long board A2, the force on short board F1 = UMG acceleration A1 = UG, the friction between long board and desktop F2 = u (M + m) g and the friction between short board is the force on short board F1, the resultant force on long board f = f-f1-f2 = f-umg-u (M + m) g acceleration A2 = [f-umg-u (M + m
The object with mass m is placed on the horizontal desktop, the dynamic friction factor between the object and the desktop is 1 / 3, and an oblique angle of 37 degrees to the horizontal direction is applied to the object The pull force F on the, in order to enable the object to move on the horizontal desktop, the value range of F shall be, and the maximum possible acceleration of the object moving on the horizontal desktop is
Answer: mg / 3 ≤ f ≤ 5mg / 3; 4G / 3. Analysis: when the object is subjected to four forces: F, Mg, supporting force N and friction f (1) f, the friction just reaches the maximum static friction. At this time, for the object: according to the equilibrium conditions, the horizontal direction: f1cos37 ° - F = 0 and the vertical direction: f1sin37 ° + n-mg = 0f= μ N simultaneous solution F1
An object with a mass of M is placed on the horizontal desktop, and an object is acted on the object, which is proportional to the horizontal direction θ Oblique upward of angle Under the action of F, the object moves x distance in the horizontal direction. It is known that the dynamic friction coefficient between the object and the desktop is μ, Then the following statement is correct A. The work done by pulling force F is FX B. Work done by supporting force is (mg fsin) θ) x C. The work done by friction is- μ （mg-Fsin θ) x D work done by gravity is MGX
C there is an angle between the force and the direction of motion, and the tensile force does work fcos θ* X a wrong support force does not do work in the vertical direction of motion B wrong D is the same as B wrong
An object moves to the right with the conveyor belt. When the conveyor belt suddenly stops moving, what is the direction of friction force on the object?
To the left, because when the object moves to the right with the conveyor belt, the object is stationary relative to the conveyor belt. When the conveyor belt suddenly stops moving, the object moves to the right relative to the conveyor belt, so the direction of friction force on the object is to the left
The wooden box is placed on the horizontal conveyor belt and moves at a uniform speed with the conveyor belt. Is the wooden box subject to friction?
Not affected
The wooden box also moves at a uniform speed, moving at a uniform speed with the conveyor belt
So there is no interaction between the two, so there is no friction
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