# urgent!!!!! acceleration on a string- Isaac Physics Question

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#1
Hey guys urgent help needed please anyone help me with these isaac physics please thank you.

A particle Q of mass 2.0kg is resting on a frictionless surface. It is attached to one end of a piece of elastic string, with the other end of the elastic being attached to a fixed point. Q is then pulled back and released from rest with the elastic extended 0.50m beyond its natural length.

After the particle has been accelerated, the string becomes slack. Rather than being allowed to continue in some kind of oscillatory motion, the string is cut when it first becomes slack. The particle is travelling at a speed of 4.0ms −1
when this occurs.

Assuming no losses to friction or other dissipative forces:

part A: Calculate the energy stored in the elastic before Q was released from rest.

part B: What is the maximum tension in the elastic during the process?

part c: Q then makes an elastic collision with a stationary body P and rebounds back along the same track at 3.0ms −1 .
Calculate the mass of P.

part D: Calculate the velocity of P after the collision.

part E: If Q had instead been accelerated from rest by a small motor giving a power of 40W, how long would it have taken to reach a speed of 4.0ms −1?
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1 year ago
#2
(Original post by future-doctor <3)
Hey guys urgent help needed please anyone help me with these isaac physics please thank you.

A particle Q of mass 2.0kg is resting on a frictionless surface. It is attached to one end of a piece of elastic string, with the other end of the elastic being attached to a fixed point. Q is then pulled back and released from rest with the elastic extended 0.50m beyond its natural length.

After the particle has been accelerated, the string becomes slack. Rather than being allowed to continue in some kind of oscillatory motion, the string is cut when it first becomes slack. The particle is travelling at a speed of 4.0ms −1
when this occurs.

Assuming no losses to friction or other dissipative forces:

part A: Calculate the energy stored in the elastic before Q was released from rest.

part B: What is the maximum tension in the elastic during the process?

part c: Q then makes an elastic collision with a stationary body P and rebounds back along the same track at 3.0ms −1 .
Calculate the mass of P.

part D: Calculate the velocity of P after the collision.

part E: If Q had instead been accelerated from rest by a small motor giving a power of 40W, how long would it have taken to reach a speed of 4.0ms −1?
A: We can assume conservation of energy, so kinetic energy of Q is energy stored in elastic.
B:using F=kx and E=1/2 k x^2 you should be able to use the energy and max length to calculate the max tension.
C: Conservation of momentum.
D:More Conservation of momentum
E: Use kinetic energy formula and Power * time = energy
0
1 year ago
#3
(Original post by tande33)
A: We can assume conservation of energy, so kinetic energy of Q is energy stored in elastic.
....
In physics, we don't assume conservation of energy.
Even friction is present, energy is still conserved and the law of conservation of energy still holds.
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1 year ago
#4
(Original post by Eimmanuel)
In physics, we don't assume conservation of energy.
Even friction is present, energy is still conserved and the law of conservation of energy still holds.
Your statement isn't consistent - you say that we don't "assume" it, then say that it's true.

The question says:
(Original post by future-doctor <3)
Assuming no losses to friction or other dissipative forces
So, I'm not seeing your point.
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#5
(Original post by tande33)
A: We can assume conservation of energy, so kinetic energy of Q is energy stored in elastic.
B:using F=kx and E=1/2 k x^2 you should be able to use the energy and max length to calculate the max tension.
C: Conservation of momentum.
D:More Conservation of momentum
E: Use kinetic energy formula and Power * time = energy
i am still confuse how do i find the energy stored from elastic because i only know for the elastic extended
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#6
0
1 year ago
#7
(Original post by RogerOxon)
Your statement isn't consistent - you say that we don't "assume" it, then say that it's true.

The question says:

So, I'm not seeing your point.
If it is true, there is no point of assuming it is correct. The word "assume" has the implication that it is not right.
I have not encountered a well-written physics text that assumes the conservation of energy.

The question is the question and what I am quoting is what I am quoting. If you want to "over-interpret" it, I cannot help.
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1 year ago
#8
(Original post by future-doctor <3)
Hey guys urgent help needed please anyone help me with these isaac physics please thank you.

A particle Q of mass 2.0kg is resting on a frictionless surface. It is attached to one end of a piece of elastic string, with the other end of the elastic being attached to a fixed point. Q is then pulled back and released from rest with the elastic extended 0.50m beyond its natural length.

After the particle has been accelerated, the string becomes slack. Rather than being allowed to continue in some kind of oscillatory motion, the string is cut when it first becomes slack. The particle is travelling at a speed of 4.0ms −1
when this occurs.

Assuming no losses to friction or other dissipative forces:

part A: Calculate the energy stored in the elastic before Q was released from rest.

part B: What is the maximum tension in the elastic during the process?

part c: Q then makes an elastic collision with a stationary body P and rebounds back along the same track at 3.0ms −1 .
Calculate the mass of P.

part D: Calculate the velocity of P after the collision.

part E: If Q had instead been accelerated from rest by a small motor giving a power of 40W, how long would it have taken to reach a speed of 4.0ms −1?
Hello, where did you find this in Isaac Physics?
0
1 year ago
#9
(Original post by future-doctor <3)
Please post your thinking and what you have done in regard to the question.
I believe in isaac physics website there are hints and have you read the hints.
If yes, explain what is confusing you in hints.
0
1 year ago
#10
(Original post by Eimmanuel)
If it is true, there is no point of assuming it is correct. The word "assume" has the implication that it is not right.
I have not encountered a well-written physics text that assumes the conservation of energy.

The question is the question and what I am quoting is what I am quoting. If you want to "over-interpret" it, I cannot help.
Sorry, but none of that makes sense. Let's move on though.
Last edited by RogerOxon; 1 year ago
0
1 year ago
#11
(Original post by future-doctor <3)
(Original post by future-doctor <3)
A particle Q of mass 2.0kg is resting on a frictionless surface. It is attached to one end of a piece of elastic string, with the other end of the elastic being attached to a fixed point. Q is then pulled back and released from rest with the elastic extended 0.50m beyond its natural length.

After the particle has been accelerated, the string becomes slack. Rather than being allowed to continue in some kind of oscillatory motion, the string is cut when it first becomes slack. The particle is travelling at a speed of 4.0ms −1
when this occurs.

Assuming no losses to friction or other dissipative forces:

part A: Calculate the energy stored in the elastic before Q was released from rest.

part B: What is the maximum tension in the elastic during the process?

part c: Q then makes an elastic collision with a stationary body P and rebounds back along the same track at 3.0ms −1 .
Calculate the mass of P.

part D: Calculate the velocity of P after the collision.

part E: If Q had instead been accelerated from rest by a small motor giving a power of 40W, how long would it have taken to reach a speed of 4.0ms −1?
A: This is wholly transferred to KE;
B: The tension is linear with extension, so calculate the average force, and, from that, find the maximum;
C: Look at the definition of an elastic collision.
D: As above;
E: You know the mass and change in KE, so can calculate the time for the motor to provide that.
1
1 year ago
#12
(Original post by Eimmanuel)
In physics, we don't assume conservation of energy.
Even friction is present, energy is still conserved and the law of conservation of energy still holds.
What I meant by that is that all the elastic energy becomes kinetic energy, that's all, but thanks for pointing my error in terminology!
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