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Force and Translational Dynamics
Spring force uses Hooke's law: \vec F_s=-k\Delta \vec x
k = stiffness of spring
\Delta x = displacement from measured from a relaxed length
negative sign means force points back towards equilibrium
Vertical spring stretched the spring until k\Delta x = mg at equilibrium.
Hooke's law in magnitude is |\vec F_s|=k|\Delta x|
Spring constant k measures in N/m. Bigger k means more stiff (obviously).
Spring force is a restoring force that points towards equilibrium position of object spring relationship.
For a vertical spring with hanging mass, relaxed length is not equilibrium because gravity stretches spring
Ideal Spring:
The mass of an ideal spring is treated as negligible compared to the objects attached to it.
- You can ignore the spring's own weight in calculations.
- You focus only on the interaction between the spring and the attached object.
An ideal spring follows a linear force-displacement relationship.
- The force is directly proportional to how far the spring is stretched or compressed.
- Stretch it twice as far and it pulls back with twice the force.
- This behavior stays consistent each time you use the spring.
Direction of Spring Force
When a string is stretched:
\Delta xis positive- Spring force is negative, pulling back When a string is compressed:
\Delta xis negative- Spring force is positive, pushing forward
WHEN CALCULATING THE \Delta x OF A VERTICAL SPRING WITH A HANGING MASS, USE THE RELAXED POSITION NOT THE EQUILIBRIUM POSITION.