Measuring the gravitational accelearation

International Baccalaureate Physics

Measuring the gravitational acceleration

Lab report

Planning

Apparatus

A string (about 0.5m), stop watch, bob (weight), stand with a clamp, ruler (1m), angle meter, protractor.

Variable/Constants

Constant

- Angle of release (20 degree)

- Mass of bob

- Number of Swings (20 times)

Variable

- Length of string

Method

Get a string and stick it with a small bob.
Hold the string by a clamp.
Ruler to measure the length of string.
Start from 0.49m, and decrease progressively the interval by 0.06 meter.
Record the time when the 20 swings (one single swing means a complete oscillation of the pendulum) are finished.
Record the time twice at the same length. If the time difference between the two trials is big, take one more recording to get more accurate data.
Do the experiment until the length reaches until 0.19 meter.

Data Collection

Uncertainties

For this particular experiment, there exists an ‘uncertainty’ factor.

The reason for the ‘uncertainties in measurement’ is the degree of accuracy is not really as precise it records.

In this Lab, the length of string is measured by ruler, which is an analogue scale (device) and its smallest gradation is 0.005 meter, also the time is recorded by stopwatch which is digital scale (instrument) and its smallest division is 0.01 second.

As a result, we can say that the length (in meters) has 0.005 meter uncertainty (which means the data will be rounded up ...