Spring Force


by volraithe
Tags: force, physics, spring
volraithe
volraithe is offline
#1
Jul1-09, 03:58 PM
P: 1
A 1.54-kg 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.
Phys.Org News Partner Science news on Phys.org
Lemurs match scent of a friend to sound of her voice
Repeated self-healing now possible in composite materials
'Heartbleed' fix may slow Web performance
Pengwuino
Pengwuino is offline
#2
Jul1-09, 04:52 PM
PF Gold
Pengwuino's Avatar
P: 7,125
Quote Quote by volraithe View Post
A 1.54-kg 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.
Doing that will only give you the instantaneous acceleration. The problem with this is that the force will change continuously as the mass is pushed with the spring; this results in a constantly changing acceleration and we can't use our kinematics very easily. We want to use something else.

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.


Register to reply

Related Discussions
spring force Classical Physics 2
spring force Introductory Physics Homework 8
spring force Introductory Physics Homework 2
Where does the spring force come from? General Physics 9
Spring Force Advanced Physics Homework 1