Physics · Practical apparatus

Loaded metre-scale depression

Place a metre scale on two supports and add load at its midpoint. Depression grows with span cubed and decreases with thickness cubed; use modest loads within elastic bending.

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Loaded metre-scale depression

மைய நிறையால் தாங்கிய அளவுகோல் வளையும். தாங்கு நீளத்தின் மும்மடங்குச் சக்தி படியும்; தடிமனின் மும்மடங்கிற்கு எதிர்விகிதம்.

Key notes, relationships and model limits

Key relationship

δ=FL³/(48EI); I=bd³/12.

Practical tip

Place a metre scale on two supports and add load at its midpoint. Depression grows with span cubed and decreases with thickness cubed; use modest loads within elastic bending.

Common trap

Beam thickness enters the area moment as d³; orientation and support arrangement matter for the deflection formula.

Model limits

simply supported rectangular elastic beam, point central load, small deflection. Very flexible settings may exceed this assumption; self-weight deflection is subtracted by tare.

What you will learn

Adjust loaded metre-scale depression apparatus, observe its reading and derive the indicated physical quantity.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

For 0.5 kg, L=0.8 m, b=25 mm, d=4 mm and E=10 GPa, δ≈3.14 mm.

Why this matters

The model connects loaded metre-scale depression with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

Doubling scale thickness at fixed load and span makes deflection?

One half as large.
One eighth as large.
Eight times larger.

Read the explanation

One eighth as large.

Course connection: Virtual apparatus preparation. Check exact board/exam membership in the syllabus sources. Physical practical work remains necessary.