Impulsive Tensions Homework: 2 Masses, 6m/s Velocity

  • Thread starter Bucky
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In summary, the problem involves two small bodies, A and B, with masses 1kg and 2kg respectively, joined by a light inelastic string on a smooth horizontal table. When A is projected horizontally away from B with a velocity of 6m/s, the string becomes taut. The speed of B after this stage is equal to 2m/s, the impulsive tension in the string is 4N/s, and the loss in kinetic energy is not specified. The calculation for the impulsive tension can be done using either particle A or B, and it is unclear why the example in the lecture notes only uses one particle. If there were more than two particles in the system, the impulse can still be calculated
  • #1
Bucky
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Homework Statement


Two small bodies A and B with masses 1kg and 2kg respectively are placed side-by-side on a smoooth horizontal table and are joined by a light inealstic string. A is projected horizontally away form B with a velocity of 6m/s. i)Determine the speed of B after the string becomes taut,
ii)the impulsive tension in the string,
iii)and the loss in kinetic engergy at this stage.


Homework Equations





The Attempt at a Solution



got all three parts ok, but i don't follow the answer for part ii (and in my opinion not understanding is just as bad as getting the wrong answer).

in my notes i have...


v = 0
u = 2m/s
(from i)


Impulsive Energy:

For B: 2u = T
2(2) = T
T = 4N/s


why is this only calculated for B? Since it's the energy in the string I thought it would be the energy in the whole system? or some sort of balance?

In the lecture notes example it seems the impulse is only calculated for the other particle in the system. why? also what would happen if you had 3+ particles in the system?
 
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  • #2
The problem statement asks for "impulsive tension" and your solution talks about "impulsive energy", but neither term is correct, and your units are not correct. What is the definition of Impulse? You can calculate it using particle A or B.
 
  • #3



I would first clarify that the impulsive tension in a string is calculated for each individual object attached to the string, not for the entire system. This is because the tension in the string is what causes the change in velocity for each individual object, not the entire system as a whole.

In this specific scenario, the impulsive tension is only calculated for object B because it is the one experiencing a change in velocity due to the tension in the string. Object A is already moving at a constant velocity of 6m/s and does not experience a change in velocity.

If there were 3 or more objects attached to the string, the impulsive tension would be calculated for each individual object that experiences a change in velocity due to the tension in the string.

Additionally, the impulsive tension is not the same as the energy in the string. The impulsive tension is a force that is applied to the objects, while the energy in the string is a measure of the total kinetic energy of the objects attached to the string. The impulsive tension is used to calculate the change in velocity, while the energy in the string is used to calculate the loss in kinetic energy.

I hope this clarifies the concept of impulsive tension and its calculation in this scenario. If you have any further questions or need clarification, please feel free to ask.
 

1. What is "Impulsive Tensions Homework"?

"Impulsive Tensions Homework" is a physics problem that involves calculating the tension and forces acting on two masses that are connected by a string or rope. The problem assumes that the masses are moving with an initial velocity of 6m/s and experience a sudden change in velocity due to an impulse force.

2. How do I solve "Impulsive Tensions Homework"?

To solve this type of problem, you will need to use Newton's Second Law of Motion, which states that the sum of all forces acting on an object is equal to the mass of the object times its acceleration (F=ma). You will also need to use the concept of impulse, which is the change in momentum of an object due to an external force. By setting up equations and solving for the unknown variables, you can determine the tension and forces acting on the masses.

3. What are the key concepts involved in "Impulsive Tensions Homework"?

The key concepts involved in this problem are Newton's Second Law of Motion, impulse, and the equations for calculating these values. You will also need to understand the concept of tension, which is a pulling force exerted by a rope or string, and how it relates to the forces acting on the masses.

4. What are some common mistakes when solving "Impulsive Tensions Homework"?

Some common mistakes when solving this type of problem include not properly setting up the equations, not considering all the forces acting on the masses, and not understanding the concept of impulse. It is also important to pay attention to units and make sure they are consistent throughout the problem.

5. How can I check my answer for "Impulsive Tensions Homework"?

You can check your answer by plugging your values into the original equations and making sure they are equal. You can also use the concept of conservation of momentum, which states that the total momentum before and after a collision must be equal. Additionally, you can use online calculators or ask a teacher or classmate to verify your answer.

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