Find the Tension and Acceleration of Cable B in Picture 3

In summary, the conversation discusses the tension and acceleration of a cable in picture 3 where one end is touching the ground and the other end has a velocity upward. The tension of the cable is not straight in this situation and it is questioned what the tension and acceleration of the cable will be. The moderator suggests that the tension may be zero at the moment the weight touches the ground, but further explanation using the laws of physics is needed. It is acknowledged that the tension may not be exactly zero at that moment due to the physical characteristics of the cable.
  • #1
arpon
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[moderator's note: moved to homework forum so no template]

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In picture 3, [itex]A[/itex] has touched the ground, so it has stopped. But [itex]B[/itex] has a velocity upward. So in this situation, the cable is not straight. What will be the tension of the cable and what will be the accelertion of [itex]B[/itex] in picture 3 ? Please explain 'why' in details.
 
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  • #2
What do YOU think the tension will be in picture 3?
 
  • #3
Philip Wood said:
What do YOU think the tension will be in picture 3?
I think, it should be 0, from my experience. But, how to explain this by the laws of physics?

I am not sure, what the tension is , just at the moment, when [itex]A[/itex] touches the ground. The cable is straight right at this moment.
 
  • #4
Cable has no tension when slack. I suppose that, if you wanted laws of Physics, you'd need to look at forces between particles in the rope.
 
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  • #5
arpon said:
I think, it should be 0, from my experience. But, how to explain this by the laws of physics?
it is zero. You should be able to show this by considering the acceleration (known, for both masses) and the forces on them.

I am not sure, what the tension is , just at the moment, when [itex]A[/itex] touches the ground. The cable is straight right at this moment.
At the exact moment that the cable touches the ground, it won't behave like the idealized perfectly inextensible cable that we've been assuming throughout the problem, so you cannot solve for the tension at that exact moment without knowing a lot more about the detailed physical characteristics of the cable. In problems of this sort, your best bet is to solve for the tension a split second before the weight touches the ground, a split second after, and not worry about what happens during the arbitrarily small time in between.
 
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1. How do you determine the tension and acceleration of Cable B in Picture 3?

To find the tension and acceleration of Cable B, we first need to identify all the forces acting on the cable. This includes the weight of the object attached to the cable, any external forces, and the tension force itself. Using Newton's second law of motion, we can then set up equations and solve for the unknowns.

2. What information is needed to calculate the tension and acceleration of Cable B?

In order to calculate the tension and acceleration of Cable B, we need to know the mass of the object attached to the cable, the angle of the cable, and any external forces acting on the object. We also need to know the acceleration due to gravity, which is typically given as 9.8 m/s².

3. How does the angle of the cable affect the tension and acceleration of Cable B?

The angle of the cable plays a crucial role in determining the tension and acceleration of Cable B. A steeper angle will result in a higher tension force and a greater acceleration, while a shallower angle will result in a lower tension force and a smaller acceleration. This is because the steeper angle increases the component of weight that is parallel to the cable, leading to a larger net force and acceleration.

4. Can the tension and acceleration of Cable B be negative?

Yes, the tension and acceleration of Cable B can be negative. This would indicate that the cable is under tension and accelerating in the opposite direction of the applied force. Negative values can also result from using a different coordinate system or a different direction as positive.

5. How do you verify the accuracy of your calculations for the tension and acceleration of Cable B?

To verify the accuracy of our calculations, we can use the equations of motion to find the velocity and displacement of the object attached to Cable B. We can then compare these values to the actual values observed in the picture or in real-life. If there is a significant difference, we may need to recheck our calculations or consider other factors that could affect the tension and acceleration of Cable B.

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