Pendulum Lab

Physics FirstGraphing Practice

Graphing in Physics

• Physics looks for RELATIONSHIPS between variables– Relationship between your independent and

dependent variable• No more connect the dots! (unless asked)

Still linear relationship!

Graphing in Physics

• 5 shapes of graphs in this class

None Direct (linear) Inverse

Exponential/Square Parabolic

Pendulum Lab

• 3 masses for bobs• String• Ruler• Stop watches• Balances for mass measurement• Lab partner

With your lab partner, obtain the materials and make a pendulum.Make observations.

White Boarding• What observations do you see about the

pendulum?

• What are some factors that might have an impact on the behavior of the pendula?

– Which of these behaviors or factors are related?

Mass of the bob

The heavier the weight, the less time it spends in motion

If you continue to hit it, it will keep goingRequires an outside force to push it

Length of the string

Amplitude/angle of dropgravity

forceLength of your fixed object

Sturdiness of fixed object

Material your string is made out of

Aerodynamics (shape) of the bob

Lighter weights swing faster

The more weight, the more momentum

If you put it in water, it will dramatically slow down

Speed decreases as it moves

Amplitude Length of String Mass of Bob

On your white board……• What are your dependent variables?– The period of the swing (T) – amount of

swings in a specific time period.• Which axis will this be graphed on?– The vertical axis ((y) axis).

• What are your independent variables?– Length (l), mass (m), amplitude (A)

• Which axis will this be graphed on?– The horizontal axis ((x) axis).

Period - The time required for one complete one crest to the next crest - measured in seconds.

Length of the pendulum is measured from the pendulum's point of suspension to the center of mass of its bob.

Amplitude is the string's angular displacement from its vertical or its equilibrium position.

With your lab partner…..• Your lab group is going to create an experiment to test

what affects a pendulum.• 3 different variables you will manipulate to test the

effects of a pendulum. – Length of String– Mass of Bob– Amplitude of drop

• For each variable you are testing, you need 3 different experiments

• EX: if testing mass: • weight #1 (3 trials)• weight #2 (3 trials)• weight #3 (3 trials)

• For each variable you are testing, you need 3 trials.

With your lab partner…..• Create your own data chart• Record all units in SI units– Grams, seconds, meters….. ect.

• Create your own graph using graph paper– EVERYONE does their own graph

• Identify the following steps of the Scientific Method:– What is your question? (what is the relationship

between your variables?)– What is your dependent variable?– What is your independent variable?– What are your constant variables?– What is your hypothesis?

Analysis/Discussion• GRAB A WHITEBOARD with your partner.• Answer the following on your whiteboard:• What were your variables?• What was your hypothesis?• What were your controls?• What conclusion did you reach about the

type of relationship your variables have?– Draw a rough sketch of your graph– Label your axes with units and title your graph!

• What/How would change to modify your experiment?