
#1
Jul109, 03:58 PM

P: 1

A 1.54kg block is held against a spring of force constant 1.47E+4 N/m, compressing it a distance of 0.100 m. How fast is the block moving after it is released and the spring pushes it away?
i thought u just use the formulas that F=kx and then plug that into F=ma, but i am not getting the right answer... anyone have any other suggestions as to what path I should take? thank you. 



#2
Jul109, 04:52 PM

PF Gold
P: 7,125

A very simple method for this problem would be to use the fact that the potential energy of the spring is [tex]\frac{{kx^2 }}{2}[/tex]. We know that upon release, the spring is going to transfer all of it's energy into the mass. We of course know the energy of a mass as [tex] \frac{{mv^2 }}{2}[/tex]. Equating both sides allows you to solve for the velocity of the mass. 


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