Calculate the total attack of gravity and friction
Publish: 2021-04-23 19:32:52
1. plus
2. The friction is only related to the pressure. It has nothing to do with gravity
analysis:
when the object moves on the horizontal ground, the friction force is related to the pressure and the gravity. Because for an object standing on a horizontal surface, the pressure is equal to gravity
when the object moves on the inclined plane, the friction force is related to the pressure, but not to the gravity. Because on the slope, pressure is not equal to gravity< So: the friction force is related to the pressure.
analysis:
when the object moves on the horizontal ground, the friction force is related to the pressure and the gravity. Because for an object standing on a horizontal surface, the pressure is equal to gravity
when the object moves on the inclined plane, the friction force is related to the pressure, but not to the gravity. Because on the slope, pressure is not equal to gravity< So: the friction force is related to the pressure.
3. As long as the pressure branch generated by gravity is not zero and the contact surface is not deformed by pressure, the relationship between gravity and friction is proportional.
4. If there is no friction coefficient, we don't know whether we can push or not, f = UMG (friction coefficient when u)
but if we can't push, friction is equal to thrust, and push friction is equal to UMG
friction can be divided into dynamic friction and static friction
if there is no relative motion, there is no dynamic friction
dynamic friction f = UMG (U is dynamic friction coefficient 0 < U < 1), which is also the maximum static friction
/>If there is no dynamic friction coefficient, the maximum static friction can not be determined
for your problem,
if the object has relative motion, then the dynamic friction = UMG (regardless of whether it is uniform or not, If there is no relative motion, then the static friction is always equal to the thrust, so that the two forces can be balanced
the above is the theory. Let's analyze your problem
the first one is g = 10, f = 3. Because 0 < U < 1, then the maximum static friction in the range of 0 < f < 10N may be less than or greater than f, so we can't judge whether it is moving or not As you said, even if the motion is a straight line with uniform velocity, the size of F can be determined as 3N (force balance)
similar to question 23, the maximum static friction must be less than the thrust F, so the object must move, but it can not be uniform. Because the thrust is greater than the friction, these two questions can judge whether the object can push, but can not determine the friction
but if we can't push, friction is equal to thrust, and push friction is equal to UMG
friction can be divided into dynamic friction and static friction
if there is no relative motion, there is no dynamic friction
dynamic friction f = UMG (U is dynamic friction coefficient 0 < U < 1), which is also the maximum static friction
/>If there is no dynamic friction coefficient, the maximum static friction can not be determined
for your problem,
if the object has relative motion, then the dynamic friction = UMG (regardless of whether it is uniform or not, If there is no relative motion, then the static friction is always equal to the thrust, so that the two forces can be balanced
the above is the theory. Let's analyze your problem
the first one is g = 10, f = 3. Because 0 < U < 1, then the maximum static friction in the range of 0 < f < 10N may be less than or greater than f, so we can't judge whether it is moving or not As you said, even if the motion is a straight line with uniform velocity, the size of F can be determined as 3N (force balance)
similar to question 23, the maximum static friction must be less than the thrust F, so the object must move, but it can not be uniform. Because the thrust is greater than the friction, these two questions can judge whether the object can push, but can not determine the friction
5. No friction coefficient
you don't know whether you can push or not
F = UMG (friction coefficient when u)
but if you can't push, friction is equal to thrust
pushing friction is equal to UMG
friction is divided into dynamic friction and static friction
if the object doesn't move relative to each other, there is no dynamic friction
dynamic friction f = UMG (U is dynamic friction coefficient 0 < U < 1), which is also the maximum static friction Force
if there is no dynamic friction coefficient, the maximum static friction can not be determined
for your problem,
if the object has relative motion, then the dynamic friction = UMG (regardless of the uniform speed, If there is no relative motion,
then the static friction is always equal to the thrust so that the two forces can be balanced
the above is the theory
let's analyze your problem
the first g = 10
F = 3
because 0 < U < 1
then the maximum static friction in the range of 0 < f < 10N
may be less than f or greater than f
so it is not necessary It can judge whether the object is moving or not
but as you said that even the motion is a straight line with uniform speed
the size of F can definitely be 3N
(force balance)
similar to question 2
3
the maximum static friction must be less than the thrust f
so the object must move
but it cannot be uniform
because the thrust is greater than the friction
so these two questions can judge whether the object can move, But we can't determine the amount of friction
you don't know whether you can push or not
F = UMG (friction coefficient when u)
but if you can't push, friction is equal to thrust
pushing friction is equal to UMG
friction is divided into dynamic friction and static friction
if the object doesn't move relative to each other, there is no dynamic friction
dynamic friction f = UMG (U is dynamic friction coefficient 0 < U < 1), which is also the maximum static friction Force
if there is no dynamic friction coefficient, the maximum static friction can not be determined
for your problem,
if the object has relative motion, then the dynamic friction = UMG (regardless of the uniform speed, If there is no relative motion,
then the static friction is always equal to the thrust so that the two forces can be balanced
the above is the theory
let's analyze your problem
the first g = 10
F = 3
because 0 < U < 1
then the maximum static friction in the range of 0 < f < 10N
may be less than f or greater than f
so it is not necessary It can judge whether the object is moving or not
but as you said that even the motion is a straight line with uniform speed
the size of F can definitely be 3N
(force balance)
similar to question 2
3
the maximum static friction must be less than the thrust f
so the object must move
but it cannot be uniform
because the thrust is greater than the friction
so these two questions can judge whether the object can move, But we can't determine the amount of friction
6. It's all 20n, because static / uniform speed is a balance of two forces!!
7. When gravity is the positive pressure, f = MGU, (U is the friction coefficient); When the component of gravity is a positive pressure f=tan@mgu (this formula is not necessarily, but the specific situation is analyzed).
8. There is no necessary relationship
the work done by gravity is the proct of gravity and displacement in the direction of gravity
the work done by friction is the proct of friction and displacement in the direction of friction
the work done by gravity is the proct of gravity and displacement in the direction of gravity
the work done by friction is the proct of friction and displacement in the direction of friction
9. No matter what force does work, it's a pattern w = FS. You first know the magnitude of the force depends on the direction of the force and the distance of the force acting in this direction? It depends on the direction of the force and the direction of the movement. This is the first step of the analysis
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