# M3 Spring Question help please :)Watch

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Thread starter 4 years ago
#1
Hello, I have just been stumped by the diagram needed for this question. I have checked solution bank but dont understand why they have used (0.8 + x) and (0.8 - x) for the extension of each spring. Please if possible could you help, it would be greatly appreciated!

A particle P of mass 0.4kg is attatched to two identical light elastic springs each of length 1.2m and modulus of elasticity 12 N. The free ends of the strings are attatched to points A and B which are 4m apart on a smooth horizontal surface. The point C lies between A and B with AC = 1.4m and CB = 2.6m. The particle is held at C and released from rest.

a) show that P moves with SHM
0
4 years ago
#2
(Original post by _bindra)
Hello, I have just been stumped by the diagram needed for this question. I have checked solution bank but dont understand why they have used (0.8 + x) and (0.8 - x) for the extension of each spring. Please if possible could you help, it would be greatly appreciated!

A particle P of mass 0.4kg is attatched to two identical light elastic springs each of length 1.2m and modulus of elasticity 12 N. The free ends of the strings are attatched to points A and B which are 4m apart on a smooth horizontal surface. The point C lies between A and B with AC = 1.4m and CB = 2.6m. The particle is held at C and released from rest.

a) show that P moves with SHM
Heya, I'm going to put this in the Maths forum for you as you should get more responses there.You should also check out the forum to see if there's any other threads there which might be helpful to you!http://www.thestudentroom.co.uk/forumdisplay.php?f=38
0
4 years ago
#3
(Original post by _bindra)
Hello, I have just been stumped by the diagram needed for this question. I have checked solution bank but dont understand why they have used (0.8 + x) and (0.8 - x) for the extension of each spring. Please if possible could you help, it would be greatly appreciated!

A particle P of mass 0.4kg is attatched to two identical light elastic springs each of length 1.2m and modulus of elasticity 12 N. The free ends of the strings are attatched to points A and B which are 4m apart on a smooth horizontal surface. The point C lies between A and B with AC = 1.4m and CB = 2.6m. The particle is held at C and released from rest.

a) show that P moves with SHM
At the midpoint of AB (the equilibrium position), each spring will have extension (4-1.2-1.2)/2=0.8

If we take x to be the displacement from the midpoint of AB, then the extension are 0.8+x, and 0.8-x
0
Thread starter 4 years ago
#4
(Original post by ghostwalker)
At the midpoint of AB (the equilibrium position), each spring will have extension (4-1.2-1.2)/2=0.8

If we take x to be the displacement from the midpoint of AB, then the extension are 0.8+x, and 0.8-x
oh I see, thank you very much
1
4 years ago
#5
(Original post by _bindra)
oh I see, thank you very much
Note that the equilibrium is in the middle of AB because the strings are identical. If they were not, you'd have to work out where the equilibrium position was and measure x from there.
0
Thread starter 4 years ago
#6
(Original post by tiny hobbit)
Note that the equilibrium is in the middle of AB because the strings are identical. If they were not, you'd have to work out where the equilibrium position was and measure x from there.

Brilliant! Thanks a lot
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