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Accepted
Confusion in kinetic and static friction difference and approaching problems
I don't know how to know when to apply kinetic friction and when to apply static friction
If two objects are moving relative to one another (which they are here, since the blocks are sliding down the ...
- 57.5k
3
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Why is the work done by a force on a rigid body zero if the displacement of point of application of force is zero?
The work done by a force refers to the displacement vector of the application point of that force: you cannot arbitrarily change it. So it is wrong to use the displacement vector of the center of mass....
- 75.5k
3
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Stacked block problem & static friction
My understanding is that the only friction source is between the two blocks, gravity is included, and there is a friction coefficient $\mu$.
I think your confusion is about how to put forces on a free ...
- 737
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Stacked block problem & static friction
I mean that in physics it’s taught that static friction is always
equal and opposite to the applied force, so that the body can’t move
due to friction.
You need to be careful in identifying the "...
- 75.6k
3
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Confusion in kinetic and static friction difference and approaching problems
Simple answer: for static friction, people tend to loosely say, "$f = \mu N$" but what they really mean is "$|f| <= \mu N$". You don't necessarily know what the force of static ...
- 737
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Why does a rolling ball slow down?
The ball slows down due to rolling resistance. That resistance equals the normal force times the coefficient of rolling resistance.
Rolling resistance occurs due to inelastic deformation of the ball ...
- 75.6k
2
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Two different friction coefficients. How contribute?
Static friction is similar to the reaction force that keeps the object from sinking through the table. Gravity pushes the object down, and the table pushes up with a force just strong enough to keep ...
- 42.5k
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Why does a rolling ball slow down?
When a ball or other object is sitting still, the normal force does pass through the center of mass. You can see this must be so from your diagram. If it did not, there would be a torque and the ball ...
- 42.5k
1
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What is the Bike Speed vs. Wind Speed Equation?
About ten years ago, I wrote some computer code to do something like this. Unless the course is dead flat, you will want to account for elevation change too, because it will have significant effects ...
- 737
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Accepted
Why does a rolling ball slow down?
If the ball rolls without slipping while slowing down, there must be:
a net torque acting to reduce its rotation rate ($\tau = I \frac{d \omega}{d t}$) and
a net force acting to reduce its velocity ($...
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Why does a rolling ball slow down?
See in the figure center of mass has nothing to do with it, since this ball will slow down due to the rotational resistance and frictional forces applying on it (F) (I feel sorry for not putting a ...
1
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Confusion in kinetic and static friction difference and approaching problems
Is the friction here kinetic since the blocks are moving down. I don't
know how to know when to apply kinetic friction and when to apply
static fricion. When motion is given I understand and use ...
- 75.6k
1
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Why are my heavier objects sliding on a smaller incline than lighter objects? Coefficient of Static Friction
I think the reason is to do with indentation. If you place a heavy object of a soft surface for a while the object sinks into the surface and leaves an indentation or impression of the object when it ...
- 7,398
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Why are my heavier objects sliding on a smaller incline than lighter objects? Coefficient of Static Friction
I have written similar things in other answers. But getting this message out depends on repeating it to some extent.
A John Yeager, a well-respected rock mechanics expert, has a famous quote that ...
- 737
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Does higher speed increase the cornering radius for a given steering angle
I'm not going to use the term "slip" because cornering on rubber tires is a little complicated. A good intuitive explanation is here.
https://www.yourdatadriven.com/tyre-slip-angle-...
- 737
1
vote
Accepted
Why static friction can act on centre of mass acceleration but similar force can not
In the first scenario, the resultant force is $F_R = F_{CM}-F_{fr}$. In the second one, it is: $F_R = -F_{fr}$ (supposing the same force of static friction). The acceleration of the centre of mass is $...
- 16.8k
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vote
Accepted
Minimum work done on a mass to take it along a path
If the particle begins and ends at rest, there is no change in kinetic energy which means the net work done by all external forces on the particle (gravity, friction and the applied force) is zero, ...
- 75.6k
1
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Why is the work done by a force on a rigid body zero if the displacement of point of application of force is zero?
Why is the work done by a force on a rigid body is zero if the
displacement of point of application of force is zero?
Because in order for the force to do work on a body, the source of that force ...
- 75.6k
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