# Hooke's law questionWatch

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#1
Can someone see if I'm doing anything wrong on this question? It is:

A light spring has modulus of elasticity 0.75N. One end is attached to a ceiling, the other to a particle of weight 0.03N which hangs in equilibrium below the ceiling. In this situation, the length of the spring is 49 cm. Find the natural length of the spring.

So I've gotten the equation

0.03N = (0.75(0.49 - L))/L

where L is the natural length. This rearranges to

0.03L = 0.3685 - 0.75L

To give a value for L = 0.471 (3 s.f.)

The textbook disagrees and gives answer 42cm. Have I done something wrong? I set the extension as 0.49m - L, but this seems valid.

0
1 week ago
#2
(Original post by theeetimdoherty)
Can someone see if I'm doing anything wrong on this question? It is:

A light spring has modulus of elasticity 0.75N. One end is attached to a ceiling, the other to a particle of weight 0.03N which hangs in equilibrium below the ceiling. In this situation, the length of the spring is 49 cm. Find the natural length of the spring.

So I've gotten the equation

0.03N = (0.75(0.49 - L))/L

where L is the natural length. This rearranges to

0.03L = 0.3685 - 0.75L

To give a value for L = 0.471 (3 s.f.)

The textbook disagrees and gives answer 42cm. Have I done something wrong? I set the extension as 0.49m - L, but this seems valid.

Can't see anything wrong with your working. My conclusion would be the book is in error.
1
1 week ago
#3
Which textbook/exercise/question is this from?
0
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