Physics Sba 4.doc

Physics SBA # 3: Acceleration due to gravity (pendulum) Aim: To determine a value for acceleration due to gravity [g] using the simple pendulum Diagram:

Method 1. Attach string to the pendulum bob to from a pendulum [measure and record the length of pendulum – this starting length should be the longest (50-100 cm)] 2. Measure and record the time [period] for 30 oscillations [1 oscillation is the movement of the pendulum from one extreme to the next and back] 3. Repeat step 2 two more times recording all results. 4. Shorten the pendulum [the length by which the pendulum is shortened must be chosen carefully to allow repeated shortening by the same amount] and record the new length. Repeat steps 1 – 3 5. Repeat step 4 three more times recording all results Results Length [m] 1.0 0.9 0.8 0.7 0.6 0.5

Calculations

Time 1

Time 2

Time 3

For length A average time for 20 oscillations =

Time for 1oscillation =

= TA

=D

[Time for 1 oscillation] squared = D2 REPEAT FOR ALL LENGTHS!!!

Graph Plot a graph of length l [y] against time squared D2[x].

Questions & further calculations Q1 – What is the gradient of the graph? – include units! Q2 – Calculate the value for acceleration due to gravity using the formula [g= 4π 2 • m] ; where m is the gradient of the graph. Q3 – What can be done to make the value of g more accurate?