ELASTICITY NOTES
ELASTICITY - The ability of an object to return to its original shape
after a deforming force is removed.
FOUR (4) types of Elasticity:
1. Extension – stretch  ex. Trampoline spring
2. Compression – squeeze  ex. Shock absorber
3. Torsion – twist  ex. Rat Trap
4. Flexion – bend  ex. Diving board
Robert Hooke - In 1678, Robert Hooke studied elasticity. He found
that within the limits of perfect elasticity, strain is directly proportional
to stress. This ratio is known as Hooke’s Law.
Δ (Delta) – The Greek letter for “D” and signifies the change in a value of
a given unit.
STRESS ΔF - The applied force, the weight of the object causing the
spring to stretch. Stress is always measured in units called Newtons (N)
STRAIN ΔL - The change in shape, the amount of stretch measured in
the spring. Stretch is always measured in units of centimeters (cm) or
meters (m)
ELASTIC LIMIT - The point at which too much stress is applied and
the spring will not return to its original shape.
Formulas:
What is the formula and label for Change in Force (ΔF)/Stress?
ΔF = K x ΔL (Label Newtons)
What is the formula and label for Change in Length (ΔL)/Strain?
ΔL = ΔF / K (Label m)
What is the formula and label for Elastic Constant (K)?
K = ΔF / ΔL (Label N/m = Newton/Meters)
ELASTICITY NOTES
F
K
L