Can static friction cause an accelerating train to stay on its tracks?

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Homework Help Overview

The discussion revolves around the concept of static friction and its ability to do work, particularly in the context of a box inside a speeding or accelerating train. Participants are exploring the implications of static friction in circular motion and its role in the dynamics of objects in motion.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss whether static friction can do work, with some suggesting that it cannot due to the lack of displacement in the direction of the force. Others propose scenarios where static friction might do work, such as a box in a train, raising questions about the conditions under which this occurs.

Discussion Status

The discussion is active, with various interpretations being explored. Some participants assert that static friction cannot do work, while others provide counterexamples involving a box in a train. There is an ongoing inquiry into the conditions of motion and the role of static friction in different scenarios.

Contextual Notes

Participants are questioning the definitions and assumptions related to static friction and its effects in accelerating frames of reference. There is a focus on the nuances of motion and the specific conditions under which static friction may or may not perform work.

jack1234
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Question
Can static friction do work? If no, explain why, if yes, give an example.

Attempts
What I am thinking is when the car do circular motion , it does not slip off the road because the road provides the static frictional force as the centripetal force.

However, static friction actually does not move the car for any distance, hence I am not
sure this is an answer. If yes, why it is? If no, may I know what is the correct answer?
 
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That's the answer. There is no motion of the car in the direction static friction is acting (that's why it's 'static'). If there is no motion along the direction of a force, then the force does no work.
 
Do you mean the answer for question is:
No, static friction cannot do work, because the force does not move the object through any distance?
 
Last edited:
Yes, static friction cannot do work.
 
jack1234 said:
Question
Can static friction do work? If no, explain why, if yes, give an example.

Attempts
What I am thinking is when the car do circular motion , it does not slip off the road because the road provides the static frictional force as the centripetal force.

However, static friction actually does not move the car for any distance, hence I am not
sure this is an answer. If yes, why it is? If no, may I know what is the correct answer?

It is possible for static friction to do work on an object!

Consider a box inside a speeding train. Imagine that the box is not sliding.
The kinetic energy of the box is increasing. The normal and gravitational forces do not work on the box (they are perpendicular to the motion). But the static friction force is in the direction of the motion and it does positive work on the box.
 
nrqed said:
It is possible for static friction to do work on an object!

Consider a box inside a speeding train. Imagine that the box is not sliding.
The kinetic energy of the box is increasing. The normal and gravitational forces do not work on the box (they are perpendicular to the motion). But the static friction force is in the direction of the motion and it does positive work on the box.

Ummm. Right. I was think about the question much too narrowly. Thanks for the correction.
 
nrqed said:
It is possible for static friction to do work on an object!

Consider a box inside a speeding train. Imagine that the box is not sliding.
The kinetic energy of the box is increasing. The normal and gravitational forces do not work on the box (they are perpendicular to the motion). But the static friction force is in the direction of the motion and it does positive work on the box.

How is static friction in the motion direction?
Is the train accelerating or not?

I am not so sure about this?

Casey
 
Saladsamurai said:
How is static friction in the motion direction?
Is the train accelerating or not?

I am not so sure about this?

Casey

In place of 'speeding train' write 'accelerating train'.
 

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