Physics Practicals - For Class IX (Science Group) PRACTICAL 04: To study the relation between "Load" and "Extension" of a helical spring by drawing a Graph.

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PRACTICAL 04:

To study the relation between "Load" and "Extension" of a helical spring by drawing a Graph.

APPARATUS:

• Elastic spring (Helical spring)
• Hooke's Law stand with scale
• Slotted weights
• Pointer

THEORY:
ELASTICITY:
The property of a body to regain its original shape when deforming force have been removed called elasticity.

STRESS:
Recovering force per unit area called stress. Its units is Newton per square meter (N/m²).

STRAIN:
Fractional changes in length, volume or shape called strain. Change in length per unit original length is called linear stress.

HOOKE'S LAW:
Within elastic limits stress is directly proportional to strain.

Stress ∝ Strain

^Stress / _Strain = Constant

Within elastic limit the applied force (load) is directly proportional to extension.

 Extension (F) ∝ Load (l)

F = kl

^F / _l = k

METHOD: (1.5 MARKS)

• Place iron stand on horizontal surface and suspend spring with the help of hanger of slotted weights and adjust pointer at zero.
• Add one slotted weight (of 20 gm-wt) in the hanger.
• Note down the position of pointer on the scale.
• Take five observation by increasing the load step by step each time note down the position of pointer on the scale when pointer is at rest.
• Calculate the extension of each load.
• Calculate the ratio of F/l for each observation.

OBSERVATION:

S.No.	Applied Force (F) load (gm-wt)	Pointer Reading (l) extension (cm)	F / l (gm-wt / cm)
1,
2.
3.
4.
5.

FIGURE: (1 MARKS)

GRAPH: (2 MARKS)

• Draw x and y-axis on the graph paper.
• Take load 'F' on x-axis and extension 'l' on y-axis.
• Supply suitable scale. Plot values of 'F' and 'l' from observation column.
• Draw line, which join the points.

(Note: This is a sample graph with assuming readings. The graph should be in a straight line if correct readings are obtained.)

RESULT: (0.5 MARKS)
Since ratio between "F" and :l" is constant and graph between F and l is a straight line therefore load and extensions are directly proportional to each other.

PRECAUTIONS:

• Stand must be vertical.
• Turns of the spring should not overlap each other.
• Pointer reading must be taken by keeping the eye at its level.

Special Thanks to Sir Sajjad Akber Chandio