To Determine Value Of ‘g’ At Lab By Using Simple Pendulum. | Grade Xi

APPARATUS REQUIRED

• Simple pendulum
• Stopwatch/Time
• Meter stick/Ruler
• String/Thread
• Mass (for the pendulum bob)
• Protractor (optional)

CHEMICALS REQUIRED

Not required

THEORY

A simple pendulum is a mass (bob) suspended by a string or thread from a fixed pivot point. When the pendulum is pulled back from its equilibrium position and released, it will swing back and forth. The period of oscillation (T) of a simple pendulum is the time taken for one complete cycle (from one extreme to the other and back). The period of oscillation is related to the length (L) of the pendulum and the acceleration due to gravity (g) by the following equation: T² = (4π² / g) * L Solving for g, we get: g = (4π² / T²) * L

PROCESS

• Set up the simple pendulum by attaching the mass to the end of the string and suspending it from a fixed pivot point. Make sure the pendulum is free to swing without any obstructions.
• Measure the length (L) of the pendulum from the pivot point to the center of the mass.
• Displace the pendulum from its equilibrium position by pulling it back a small distance (e.g., 10-20 cm).
• Release the pendulum and start the stopwatch/timer.
• Time the pendulum for at least 20 complete oscillations (from one extreme to the other and back).
• Record the time taken for 20 oscillations (t).
• Calculate the period of oscillation (T) by dividing the time taken for 20 oscillations by 20.
• Repeat steps 3-7 for different lengths of the pendulum.
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OBSERVATIONS

The following observations can be made during the experiment:

The pendulum swings back and forth with a regular period.

The period of oscillation increases as the length of the pendulum increases.

The period of oscillation is independent of the mass of the pendulum bob.

OBSERVATION TABLE

Length of Pendulum (L)	Time for 20 Oscillations (t)	Period of Oscillation (T)
L1	t1	T1
L2	t2	T2
L3	t3	T3
...	...	...

CALCULATIONS

Calculate the acceleration due to gravity (g) for each length of the pendulum using the formula: g = (4π² / T²) * L

RESULTS

The acceleration due to gravity (g) should be approximately the same for all lengths of the pendulum. The average value of g can be calculated by taking the average of the values obtained for different lengths.

PRECAUTIONS

Ensure that the pendulum is suspended from a fixed pivot point and is free to swing without any obstructions.

Displace the pendulum from its equilibrium position by a small distance to avoid introducing excessive energy into the system.

Time the pendulum for at least 20 complete oscillations to obtain a more accurate measurement of the period.

Measure the length of the pendulum accurately using a meter stick or ruler. *

Repeat the experiment for different lengths of the pendulum to obtain a more reliable average value of g.