Tag Info

1 vote

Modelling friction as a conservative force

For systems with a Hamiltonian formulation, the Poincaré recurrence theorem (PRT) would indicate that most trajectories will eventually evolve back to a state arbitrarily close to their initial ...
• 38.1k

Modelling friction as a conservative force

It's not possible to do what you are attempting. For friction to be a conservative force, then the net work done by moving along a path where the start and endpoints are the same is zero which would ...
• 569

Modelling friction as a conservative force

Adding friction to a Lagrangian is not commonly taught. It is non-trivial, but not too difficult in the end. The key element is producing a "dissipation function" $D$ that we can use to ...
• 65.6k

Can we have motion in systems where inertia is neglected?

I'm not completely sure I fully understand your question, but I'll try to give you an answer... It might help to think of this problem in a pseudo-relativistic context, wherein the physical motion of ...
• 184
1 vote

Can we have motion in systems where inertia is neglected?

We sometimes assume a body has negligible mass, such as a rope in a pulley system where the pulley and weights on the ends of the rope have much greater mass than the light rope. This simplifies the ...
• 6,388
1 vote

Can we have motion in systems where inertia is neglected?

It is not clear what is meant by inertia is neglected: Small/huge inertia It could be that the inertia is so small, that particle experience huge acceleration. We do often use this kind of an ...
• 38.8k
1 vote

Can friction or normal force be undetermined?

In general, there is no reason why all the reaction forces can be determined in a problem. Your intuition is biased by all the exercises you were assigned in an academic setting, which were hand-...
• 1,647

Energy dissipated by friction and entropy

It would be correct to assume that the entropy increase of the universe after the block has stopped is: $$\Delta S = \frac{K}{T}$$ In response to my query, you indicated that the "ambient ...
• 56k

Can the value of friction force ever exceed value of applied force?

First, there is an important qualification to "the value of friction force can never be greater than the applied force". This refers to static friction. Indeed, you pose a scenario where &...
• 3,365

Can the value of friction force ever exceed value of applied force?

To answer the question in the title, the friction force can be larger than the normal force that is producing it. There is no restriction. Coefficients of friction larger than 1 are not common in ...
• 6,568

Can the value of friction force ever exceed value of applied force?

No. You've discovered the Class 2 Lever, which places the load between the input force and the fulcrum. You have correctly calculated that the friction force is 4 times the input force. The reason for ...
• 8,972
Accepted

How to know the direction of static friction with angular momentum?

In this case, the static friction is responsible for generating the circulation in the case of rolling without slipping. The reverse occurs when friction is a resistance to rolling. This is similar to ...
• 278

Energy dissipated by friction and entropy

It would be correct to assume that the entropy increase of the universe after the block has stopped is: $$\Delta S = \frac{K}{T}$$ This would be correct only provided the temperature of the "...
• 28.4k
1 vote
Accepted

Will the inner gimbal continue to rotate if no friction?

In order for the gyroscopic effect to be elicited motion is required. When the rotation rate of the outer gimbal goes back to zero the gyroscopic response to it ceases. Later edit: In writing the ...
• 15.3k
1 vote

Energy dissipated by friction and entropy

If the initial temperature and the final temperature of the block are both T, then applying the complete version of the first law of thermodynamics to the block gives $Q=-K$, where Q is the amount of ...
• 27.9k

Checking whether my conclusion are correct or not regarding turning of car/bike on flat road

No, first statement is not true. The number of friction forces which are acting here are 2, i.e one along the circular path which is making the car move even if it's not being accelerated (although ...
• 672

Work done by static friction on a car

The answer by @stafusa is correct. The increase in kinetic energy (KE) of the car is due to the decrease in internal energy of the car (from combustion, batteries, etc.) This can be understood using ...
• 6,388
1 vote

• 56k
1 vote

End motion of an empty spherical shell with a ball rolling on it's inner surface

Sounds like initially an external observer would see the shell not spinning, but oscillating around as the ball rolls inside. Friction will couple the motion of the ball to the rotation of the ball. ...
• 34.3k