Is Equating Energies a Better Solution for Finding Extension Under Spring Force?

[Prabs3257]

Homework Statement

An 8 kg mass hangs from a spring and and stretches it by 16 cm beyond its natural lenght find k of the spring

Relevant Equations

F=kx

Its a very basic problem and my friend suggested a solution that we should equate mg and kx ie mg=kx and just plug in m=8 and x=0.16 but i think that we should equate the energies like mgx=1/2kx^2 ie because at the point where mg will be equal to kx the mass will still have a velocity hence it will not be the final extension am i correct??

 

[haruspex]

Homework Statement: An 8 kg mass hangs from a spring and and stretches it by 16 cm beyond its natural length find k of the spring
Homework Equations: F=kx

Its a very basic problem and my friend suggested a solution that we should equate mg and kx ie mg=kx and just plug in m=8 and x=0.16 but i think that we should equate the energies like mgx=1/2kx^2 ie because at the point where mg will be equal to kx the mass will still have a velocity hence it will not be the final extension am i correct??

It "hangs from", not "is attached to and then released", so it describes a static condition.

 

[Prabs3257]

Oh ok now i get it thanks

 

[Prabs3257]

It "hangs from", not "is attached to and then released", so it describes a static condition.

if it was written is attatched to and then released then we would conserve energy right ?? If yes then Coz of the same reason i gave right ??

 

[haruspex]

if it was written is attatched to and then released then we would conserve energy right ?? If yes then Coz of the same reason i gave right ??

Yes, if we read the given extension as being the maximum.