Simple Pendulum Lab Report: Determining Acceleration Due to Gravity, Summaries of Physics

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D. H. Loyd,

Simple pendulum lab report

Simple Pendulum

Purpose: The purpose of this lab is to find acceleration due to gravity using a simple pendulum. Theory: Acceleration due to gravity is the acceleration gained by an object due to gravitational force. For example, when an object falls towards the ground from a height, the object’s velocity changes. This change in velocity produces acceleration in the object. This is denoted by the letter “g”. The value of acceleration due to gravity is g = 9.8m/s^2. This concept of acceleration due to gravity is explained further in the lab using a simple pendulum. A simple pendulum uses a bob and a string. It is suspended from a fixed support. The vertical distance between the point of suspension and the center of the bob is called the effective length of the simple pendulum. This is given as the letter “l”. The figure below shows a drawing of a simple pendulum. Figure 1.1: Simple pendulum

Figure 1.3 below shows the actual formula and the truncated formula of the simple pendulum. Figure1.3: Actual and truncated formula of the simple pendulum. The truncated formula depends on the length, l, of the string and the value of gravitational force, g. The time period, T, is measured in seconds. This formula can be used if the angle of the oscillation is small. If we use a small angle, the value of sin^2 (θm/2) would be negligible and would result in 1. Therefore with the assumption of a small angle, we can use the truncated formula. Apparatus:

• Stop watch
• Meter scale
• Bob
• String
• A piece of cardboard and tape

Data Table:

Calculations:

Results and error: The experimental value for g is 966.8973cm/s^2 from the above calculations with 1.44% error compared to the ideal value. Discussion: Errors in the experiment could have resulted due to many sources. A human error could be made while measuring the time period using a stopwatch. The reaction time to observe the oscillations while starting and stopping the stopwatch could play as an error. A possible solution to improve the accuracy for this error could be to take more than one trial. The angle used to start the oscillation could also result in an error. A very small angle should be used. Another example of an error could be parallax error while measuring the length of the string with the measuring tape. Furthermore, the friction between the air and the bob movement can be a source of error. A possible solution to this would be avoiding light weighted bob and using a heavier one.