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Plan № 33
Project № 1
Science Project:
Hooke's Law:
Calculating Spring Constants
Forces cause objects
to move or deform in some
way.
Newton’s third law
states that for every
force, there is an equal and opposite force. This is
true for springs, which
store and use mechanical
energy to do work.
Springs are
elastic
, which means after they are
deformed (when they are being stressed or
compressed), they return to their original shape. Springs are in many objects we
use on a daily basis. They in ball point pens, mattresses, trampolines, and absorb
shock in our bikes and cars. According to the
Third Law of Motion, the harder
your pull on a spring, the harder it pulls back. Springs obey
Hooke’s Law
,
discovered by Robert Hooke in the 17
th
century. Hooke’s law is described by:
F = -kx
Where
F is the force exerted on the spring in Newtons (N),
k is the spring constant, in Newtons per meter (N/m),
and
x is the displacement of the spring from its equilibrium position. The spring
constant,
k, is representative of how stiff the spring is. Stiffer (more difficult to
stretch) springs have higher spring constants. The displacement of an object is a
distance measurement that describes that change from the normal, or equilibrium,
position.
Problem
Calculate the spring constant using Hooke’s law. Which spring do you think will
have the greatest spring constant? The smallest spring constant? Why?
Materials
Scale (measures grams or kilograms)
Ruler (measuring centimeters)
Different coil springs
Small weight
Wooden plank
Table or countertop
Books, or other stackable objects
Procedure
With the help of an adult, fix one end of each spring to one side of the
wooden plank. Be sure to leave a couple of inches between each spring.
Why
should one end of the spring be fixed? Arrange
some books on a table or
countertop in two stacks, about the length of the wooden plank. Place the wooden
plank on the stacks with the springs hanging down. Make sure there is still some
room between the bottom of the springs and the table. Using the centimeter side
