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# Elastric strings help please watch

1. An elastic string of natural length 2 metres and modulus of elasticity 40 newtons is stretched between two fixed pegs 4 metres apart on a smooth horizontal table. A particle of mass 0.1kg is attached to the string at its midpoint and pulled aside through a distance of 1 metre at right angles to the line joining the pegs. After the particle is released, how fast is it moving when it crosses the line joining the pegs?

2. (Original post by Fathima.hh)
An elastic string of natural length 2 metres and modulus of elasticity 40 newtons is stretched between two fixed pegs 4 metres apart on a smooth horizontal table. A particle of mass 0.1kg is attached to the string at its midpoint and pulled aside through a distance of 1 metre at right angles to the line joining the pegs. After the particle is released, how fast is it moving when it crosses the line joining the pegs?

Draw diagrams, find extension of string before and after, hence calculate elastic potential energy stored and use the principle of conservation of energy to find the speed at the end.

3. (Original post by K-Man_PhysCheM)
Draw diagrams, find extension of string before and after, hence calculate elastic potential energy stored and use the principle of conservation of energy to find the speed at the end.

What do i do now? Im confused. Should i find elastic potential energy again by using lambda as 40. Natural length as 2metres and extension as the one i found below in the picture?
Attached Images

4. (Original post by Fathima.hh)
What do i do now? Im confused. Should i find elastic potential energy again by using lambda as 40. Natural length as 2metres and extension as the one i found below in the picture?
Yes. When the string has been drawn back, it will have a larger elastic potential energy. When it is released, it will transfer some of this stored energy to the particle, so it will gain kinetic energy.

Can you go on from here?
5. (Original post by k-man_physchem)
yes. When the string has been drawn back, it will have a larger elastic potential energy. When it is released, it will transfer some of this stored energy to the particle, so it will gain kinetic energy.

Can you go on from here?
yessssss i solved it. Thank you!

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