Practical 3 - Measurement of g with a pendulum Flashcards
How is the period of a pendulum related to the length of the pendulum?
By the equation T = 2pi √l/g
How do we re-arrange the equation T = 2pi √l/g to obtain a linear equation?
Square it all
T^2 = (4pi^2/g) x l
What goes along the x-axis of the graph?
l —> length (m)
What goes along the y-axis of a graph?
T^2
What would the gradient of an l against T^2 graph be?
4pi^2/g
Method
The pendulum bob is displaced a few cm and allowed to swing freely
Crouching so that eye is perpendicular to the stand, start timing as the pendulum passes the stand in a certain direction
Count 10 oscillations and stop timing as it passes the same direction
How do we count a singular oscillation?
Counting the pendulum swinging back AND forth
What can l be measured to?
+-2mm
What is reaction time taken to be?
+-0.2s
What’s the uncertainty in reaction time for this practical?
+-0.4s, as reaction time is usually taken to be +-0.2s, so a total of +-0.4s for the start and finish times
How do we work out the % uncertainty of a value?
Uncertainty
—————— x100
Value
How do we calculate the uncertainty in T^2?
% uncertainty x2 (as it’s squared) of T^2
Where do we measure to for l?
To the middle of the sphere
What do we use to count the oscillations?
A fixed point
Name for the specific point used in this type of practical
Fiducial
