Report

Experiment to find gravity from a Pendulum Surya Tahir/BTEC National Diploma/Pendulum Experiment Covers objectives: • P3 – demonstrate the ability to plot a linear graph using scientific data • P3 – Calculate the rate of change by the most appropriate method • D1 – determine the size and influence of errors on final calculations Surya Tahir/BTEC National Diploma/Pendulum Experiment Stage 1 • Draw up a table with the following headings: Length (m) Time (1st) for 10 swings ÷ 10 Time (2nd) for 10 swings ÷ 10 Average length of time (T) 1. 2. 3. 4. 5. Surya Tahir/BTEC National Diploma/Pendulum Experiment T² Stage 2 • • • • • • Set up equipment safely Measure string at a short length One person to time 10 pendulum swings Partner to record data Do this twice Measure 5 different lengths of string Surya Tahir/BTEC National Diploma/Pendulum Experiment Stage 3 • On graph paper plot length of pendulum (l) against T² • You should have 5 sets of data points • You can now work out the gradient by choosing 2 suitable points and calculating : T² / l Surya Tahir/BTEC National Diploma/Pendulum Experiment Stage 4 • We can now find an estimate for gravity by comparing the formula for a straight line: Y=mx+c • With the formula for one complete oscillation of a pendulum: T= 2π√(l/g) Or T² = 4 π²l/g Surya Tahir/BTEC National Diploma/Pendulum Experiment Stage 4 continued.. • So gravity = • 4 π² ÷ gradient from graph Surya Tahir/BTEC National Diploma/Pendulum Experiment Stage 5 -comparison • How close were you? • • • • In the northern hemisphere.. Acceleration due to gravity… Is… 9.81m/s² Surya Tahir/BTEC National Diploma/Pendulum Experiment Stage 6 – Evaluation and write-up **Question 1 Work out the actual error and percentage error between your value and the actual value for gravity **Question 2 • Consider why we took values for 10 pendulum swings, and why this was done twice Surya Tahir/BTEC National Diploma/Pendulum Experiment