Chapter 15: Materials Flashcards
What is Hooke’s Law?
The extension of a spring, or other elasticated object,, is directly proportional to the force applied to it, as long as the elastic limit has not been exceeded.
How do you identify the limit of proportionality using a graph?
The line will be straight until this point, where it will begin to curve.
Describe an experiment to illustrate Hooke’s Law.
The unloaded length of a spring is measured. Different numbers of slotted masses are added to the spring and its new length measured each time. The extension is the new length minus the unloaded length.
What does the term elasticity mean?
the ability of an object or material to resume its normal shape after being stretched
What does a graph showing load against extension for an object that obeys Hooke’s Law look like?
The line is straight and is directly proportional. The gradient of the line is the spring constant, k.
Where may errors occur in an experiment investigating Hooke’s Law?
Random error - accidentally reading the ruler wrong
Systematic error - having a zero error constantly
How do you describe the behaviour of a spring obeying Hooke’s Law? What do you say if it doesn’t?
A spring obeying Hooke’s Law is described as being elastic, because it will return to its original length and shape once the load has been removed. However, if it doesn’t it behaves plastically, and has been permanently stretched.
