What is an elastic object?
One that regains its shape when forces deforming removed
What is extension?
It is increease in spring's length from original length
Result from spring's extension aganist force applied
Straight line throigh origin
it is directly proportional
How to get line of proportionality
spring's extension aganist force applied
Apply too big of a force , line begins to curve
exceeded line of proportionality
Elastic objects have to obey what law?
What does Hooke law states?
The extension is directly proportional to the force applied
provides limit to proportionality , not exceeded
Equation expressing Hooke's law
F - ke
F = force applied in newtons , N
k = spring constant in N/m
e = extension in m
What happens the stiffer the spring?
Greater its spring constant
What happens the elastic object is stretched?
Work is done and the elastic potential energy store of object increases
When does Hooke's law also applied to?
Elastic object when it is compressed
Steps to investigate stretch?
- Clamp string at upper end and weight haanger to keep straight
- Measure original length of spring with metre ruler
- Add weights at the bottom and measure length
- Repeating this
To investigate stretch
what do you do when each weight added?
Subtract it from original length of stretched length to give extension