# lengths of a spring

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• May 1st, 2010, 02:50 PM
DesertRose
lengths of a spring
Hi, i am given a question that states;

A spring is 20cm long when a load of 10N is hanging from it, and 30cm long when a load of 20N is hanging from it.
Draw diagrams and work out the length of the spring when;
a) there is no load on it
b)there is a load of 5 N on it.

can someone explain to me how to arrive at the answer??
any assistance would be greatly appreciated!
thank you!
• May 1st, 2010, 03:15 PM
thyristor
Look up Hooke's law.
• May 1st, 2010, 05:14 PM
organic god
Assume a linear relationship between the load and the extension of the spring, then plot the graph
• May 1st, 2010, 05:53 PM
Arcane_Mathematician
Re: lengths of a spring
Quote:

Originally Posted by DesertRose
Hi, i am given a question that states;

A spring is 20cm long when a load of 10N is hanging from it, and 30cm long when a load of 20N is hanging from it.
Draw diagrams and work out the length of the spring when;
a) there is no load on it
b)there is a load of 5 N on it.

can someone explain to me how to arrive at the answer??
any assistance would be greatly appreciated!
thank you!

You have two data points for the spring, and because of the elastic forces involved we know that the spring will elongate proportional to the load it carries. The best way to look at it is by noticing that a spring will follow an equation Length where:

is the initial length of the spring (no load),
k is the spring constant, in ,
x is the load in kg
• May 1st, 2010, 06:05 PM
DesertRose
Thank you sooo much!!
• May 1st, 2010, 06:27 PM
Arcane_Mathematician
Anytime. Post with your work whenever you're having trouble