Regents Physics

Some Kinds of Springs

Elastic Potential Energy

Energy is stored in a spring when work is done stretching or compressing it

This energy is called elastic potential energy

Compression / ElongationThe compression or elongation of a spring is the change in spring length from it’s equilibrium position when a force is applied to it

The compression (elongation) of the spring is directly proportional to the applied force…provided the elastic limit of the spring is not exceeded

Elastic Potential EnergyElastic potential energy is the energy available for use when a deformed elastic object returns to its original configuration.

2

2

1elastic PE = spring constant (distance compressed or stretched)

2

1

2elasticPE kx

The symbol k is called the spring constant, a parameter that measures the spring’s resistance to being compressed or stretched.

Spring Constant

Veritcal Moving Spring

animation

Questions to think about Where is the elastic potential

energy the max? The min? Where is GPE max? Where is EPE max?

Horizontal Moving Spring

Horizontal springs don’t contain gravitational potential energy in the system

Click for animation

EPE Practice Problem

A spring with a spring constant of 10 N/m is stretched 0.20 meters from it’s rest position. What is the potential energy stored in the spring?

1. Write Knowns/Unknown

k = 10 N/m

x = 0.20 m

2. Find equation/solve

EPE = ?

EPE = ½ kx2

EPE = ½ (10N/m)(0.20m)2

EPE = 0.2 J

Click for solution

Hooke’s Law

Fs = kx

The applied force on a spring is proportional to the distance the spring is displaced (x) and the spring constant (k)

k is the spring constant and is the constant of proportionality between the applied force and the compression/elongation of the spring

Unit is the Newton / meter

Hook’s Law Practice Problem

Hook’s Law Problem #2

Combination Problem with Springs

Gravitational potential energy and kinetic energy can turn into elastic potential energy

Question:

Describe the energy transformation that occurs during the blocks motion

End