- #1
Friction on horizontal rough surface (finding tension)
- Thread starter coconut62
- Start date
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- Tags
- Friction Horizontal Surface Tension
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Homework Help Overview
The discussion revolves around a physics problem involving tension in a system with friction on a horizontal rough surface. Participants are analyzing the forces acting on an object (B) and the implications of acceleration on tension calculations.
Discussion Character
- Exploratory, Conceptual clarification, Assumption checking
Approaches and Questions Raised
- Participants are attempting to calculate tension based on weight and acceleration, questioning how acceleration affects tension. They discuss free-body diagrams and Newton's second law in relation to the system's behavior.
Discussion Status
The discussion is active with various interpretations being explored. Some participants are providing insights into the relationship between weight, tension, and acceleration, while others are raising questions about the effects of inertia and friction on motion.
Contextual Notes
There are references to specific values and conditions, such as the mass of object B and the acceleration of the system. Participants also mention constraints like the lack of known time for certain calculations.
- #2
lep11
- 380
- 7
Since the system is accelerating.coconut62 said:
- #3
coconut62
- 161
- 1
But since the whole thing is accelerating together, why would it affect the tension?
- #4
ap123
- 265
- 0
If the weight of B was equal to the tension of the string, then the net force on B would be 0 and it would not accelerate.
Look at your free-body diagram for B and apply Newton2 to it to calculate the tension.
Look at your free-body diagram for B and apply Newton2 to it to calculate the tension.
- #5
lep11
- 380
- 7
If GB=T then acceleration would be zero.
Sorry ap123 you already said this.
Sorry ap123 you already said this.
- #6
coconut62
- 161
- 1
Ok, the acceleration of the whole thing is 1.4 and the pull of gravitational force is 9.8.
So I take the mass of B times net acceleration = 0.05 (9.8-1.4) = 0.42N.
Is it all about the "net acceleration"?
So I take the mass of B times net acceleration = 0.05 (9.8-1.4) = 0.42N.
Is it all about the "net acceleration"?
- #7
coconut62
- 161
- 1
New question
This question uses the same diagram as the previous one.
I don't know how to do (c).
When B hits the floor, A should stop accelerating and start to decelerate. But I don't know the deceleration and now it wants me to find speed. The time can't be known either.
Now the only information I have is u=2.33m/s and s= 0.5. What equation can I use?
This question uses the same diagram as the previous one.
I don't know how to do (c).
When B hits the floor, A should stop accelerating and start to decelerate. But I don't know the deceleration and now it wants me to find speed. The time can't be known either.
Now the only information I have is u=2.33m/s and s= 0.5. What equation can I use?
Attachments
- #8
ap123
- 265
- 0
When B hits the floor, what are the horizontal forces on A?
- #9
coconut62
- 161
- 1
Friction. I got the answer, thanks.
I want to ask, is this related to inertia? Is inertia partly because of air resistance/frictions?
I want to ask, is this related to inertia? Is inertia partly because of air resistance/frictions?
- #10
- 42,892
- 10,525
No. Inertia is the fact that it requires a net force to accelerate a mass. Quantitatively, it's the force divided by the acceleration.coconut62 said:
- #11
coconut62
- 161
- 1
So actually does inertia cause an object to require more force to stop/start moving?
For example, if I were to push an object of 10kg across a frictionless table, the force required for the object to start moving is due to its big mass only, or does it include inertia?
For example, if I were to push an object of 10kg across a frictionless table, the force required for the object to start moving is due to its big mass only, or does it include inertia?
- #12
- 42,892
- 10,525
coconut62 said:
It's not to do with starting and stopping as such. It is natural to think in those terms because our everyday experience is that there there is static friction to be overcome. It is to do with how much force is needed to produce a given change in speed. In principle, you could push a supertanker away from the edge of the dock, but the acceleration would be very low.
Not sure what you mean by "due to its big mass only, or does it include inertia?". Mass has two properties: masses experience gravitational attraction, and they exhibit inertia. For the purposes of your question, the inertia is the mass.