Here are some definitions to help you with your investigation.
Pendulum – a device that has a weight attached by a line or string to a fixed point that allows the weight to swing freely
Pendulum bob – the hanging weight on a pendulum
Protractor – a device used to measure angles
Degrees – a unit used to measure angles
Period – the length of time for one complete back and forth swing of a pendulum
Force – any push or pull
Gravity – a force that pulls object downward
Friction – a force that opposes the motion of an object
Resistance – opposing the motion of an object
Energy – the ability to do work
Kinetic Energy – energy due to the motion of an object
Potential Energy – energy stored due to the position of an object
Gravitational Potential Energy – energy stored in an object due to its height above the ground
Motion – the change in position of an object
Speed – how fast something is moving
Energy Transformation – to change the form of energy to a different form
Trials – repeating the same experiment multiple times
Average – a number expressing the typical value in a data set
Errors – things that could result in inaccurate or misleading results
Reading and Interpreting a Line Graph
What is a Line Graph?
A line graph is a tool that provides a picture using a line or lines to show how things change over time or how they're connected. For instance, you want to see how a plant grows over time. So you measure the plant's height every week. You can use a line graph to see how the plant is growing!
Reading and Interpreting the Graph (See Figure 1.)
• Seeing Changes: Look at the line. If it goes up, the plant is growing! If it stays flat, it's not changing its height, and if the line goes down, the plant is losing height.
• Comparing Weeks: You can easily see which weeks the plant grew the most by looking for the steepest parts of the line.
Finding the Height (See Figure 2.)
• To find the plant height at a certain week, find that Week Number on the bottom line (x-axis), go straight up to the line, and then look across to the Plant Height number on the side (y-axis). On this graph, the plant at week 6 had a height of 9 centimeters.
Extrapolating the Data Beyond the Line (See Figure 3.)
• Following the Trend: If the line is going up or down steadily, you can predict that the plant will continue changing its height at about the same rate in the next few weeks.
• Making a Prediction: You can extend the line a little bit past your last data point (see the dashed line) to make a prediction about the plant's height in the future. But remember, it's just a prediction! Things might change.
Using our extended line in this graph, we predict the plant will have a height of 7 centimeters at week 11.
• Limitations: Extrapolating too far out is not always accurate. The plant could stop growing, or grow at a different rate.
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What is a pendulum?
A pendulum is a device consisting of a weight hung from a fixed point by a line or string so the weight can swing freely back and forth.
What is a pendulum bob?
A pendulum bob is the weight hung from the fixed point attached by a string on a pendulum.
What is the period of pendulum?
The period of a pendulum is the time required for one back and forth motion of the pendulum bob.
What is periodic motion?
Periodic motion is any motion that repeats itself in equal intervals of time.
What is simple harmonic motion?
Simple harmonic motion is a special type of periodic motion in which the motion has a restoring force that is directly proportional to the displacement of the object from its resting or equilibrium position.
What is an energy transformation?
An energy transformation is the conversion of energy from one form to another form, such as from potential energy to kinetic energy.
What is kinetic energy?
Kinetic energy is energy due to the movement of an object.
What is potential energy?
Potential energy is energy that is stored due to the position of an object.
What is gravitational potential energy?
Gravitational potential energy is energy that is stored due to the vertical position of an object.
What is a net force?
The net force is the sum of all forces acting on an object.
What is friction?
Friction is a force that opposes the motion of an object.
What are unbalanced forces?
Unbalanced forces are defined as one force applied in one direction being greater than the force applied in the opposite direction.
What are balanced forces?
Balanced forces are defined as one force applied in one direction being equal to the force applied in the opposite direction.
What is speed?
Speed is how fast an object is moving or the distance traveled per unit time.
What is acceleration?
Acceleration is a measure of how fast or slowly an object is changing its motion or direction.
What is arc length?
Arc length is the distance between two points along a part of a curve or a circle.
What is the value of pi?
Although non-repeating, the value of pi can be estimated as being 3.14.
Pendulums look like very simple machines. However, understanding their motion can be difficult for some. In this investigation, you’ll determine what factors affect the motion of a pendulum and what are some conditional limitations that impact these factors.
