Form 4 - Chapter 2 : 2.12 Understanding Elasticity

Elasticity

The ability of material to resume its original shape once the force acting on it is removed.

Hooke’s Law

State that applied force is directly proportional to the extension, x of spring if its elastic limit is not exceeded.

 

 F α x

 F = k x

(k = force constant) with units N m-1

Factors That Affect the Elasticity of a material

1. Value of force constant, k 

More stiffer, more higher k.

 2. Length of spring

 The longer the spring, the more elastic will the spring be.

 3. Diameter of spring

The larger the diameter of the spring coil, the more elastic will the spring be.

 4. Diameter of spring wire

The greater the diameter of the spring wire, the less elastic will the spring be.

 5. Material of spring 

Different materials of springs will yield different elasticity. For example, a steel(keluli) spring is less elastic than a copper(kuprum) spring.

 

 

 

 

 

 

 

Form 4 - Chapter 2 : Hooke's Law (Experiment)

Hypothesis:
The bigger the weight, the longer the spring extension

Aim of the experiment:

To determine the relationship between the weight and the spring extension

Variables:

Manipulated:
Weight of the load
Responding: Spring extension
Constant: Spring constant

Apparatus and Materials:
 Spring, pin, weights, plasticine, retort stand, metre rule

Setup:

Procedure:

1. The apparatus is setup as shown in the diagram.
2. The length of the spring without any weights, l0 is measured using the metre rule with the pin as reference.
3. A 50 g weight is hung from the bottom of the spring. The new length of the spring, l is measured. The spring extension is l – l0.
4. Step 4 is repeated with weights 100 g, 150 g, 200 g, and 250 g.




Results:
Original length of spring = l0
 = __________ cm

Analysis:

A graph of spring extension, x against weight, F is plotted.

 

The x-F graph is a linear graph which passes through the origin. This shows that the
extension of the spring is directly proportional to the stretching force.

Conclusion:

Hypothesis proven.