Tip:
Highlight text to annotate it
X
During the same time period as Sir Isaac Newton lived another incredible scientist named Robert
Hooke. He discovered plant cells, invented the universal joint, and did fantastic research
involving elastics and springs.
Hooke noticed that if you stress an object with a force, the object will deform from
the strain. But as soon as you remove the stress, the object will return to it's original
shape... Just make sure you don't surpass it's elastic limit!
Think about stretching an elastic band or a spring. At first it's pretty easy to stretch
it, but the more you stretch it, the more force you have to put in to hold it there
to balance the elastic's force. Hooke came up with this relationship
F(spring) = - kx The restoring force of a spring is equal to
it's spring constant times the displacement from it's equilibrium position.
The equation needs a negative sign to take into account the fact that if you stretch
or compress a spring to the right, the restoring force would be to the left.
Check this out.
At this point the elastic is at the equilibrium position. There is no net force on the elastic.
The more I increase the displacement from the equilibrium position, the more force I
have to apply to balance the restoring force of the elastic.
Then when I let go, the restoring force takes it back in the direction of the equilibrium
position.
So now we understand about hooks law .