#### Estimated time:

`25 minutes setup, 30 minutes data collection, 30 minutes results analysis and discussion.`

# The Pirate Ship

Ahoy, Matey! The pirate ship is a welcome adventure for any carnival explorer.

In this activity, you will study the motion of a pendulum, and investigate how the length of the pendulum affects this motion. Your challenge is to design the Pirate Ship ride. Depending on how long the pendulum is, the Pirate Ship will make bigger or smaller swings. You will capture this motion using a sensor called an accelerometer, and study the results using Science Journal. It’s time to make waves!

## Material list #### 1Arduino Science Carrier Board #### 1Arduino MKR 1010 WiFi #### 2Black Sticks #### 2 Silicone Standoffs ## Material not included #### 1Android Mobile device with Science Journal installed #### 1Portable Power Bank #### 1Li-Po Battery #### 1Pencil #### 1Ruler (60cm or longer) #### 1Protractor #### 1Twine or Yarn ## Topics and keywords

• Frequency

: The number of cycles or oscillations in a specific amount of time: frequency = 1 / period.

• Acceleration

: The rate change of velocity with respect to time.

• Inertial Measurement Unit (IMU)

: An electronic sensor that measures the acceleration and rotation of an object using a combination of accelerometers, gyroscopes and sometimes magnetometers.

• Amplitude

: The maximum displacement of an object from its equilibrium position.

• Accelerometer

: A device that measures acceleration due to a force.

• Equilibrium position

: The position which an object will remain if undisturbed.

• Force

: An interaction that causes an object to be pushed or pulled in a certain direction with the effect of changing the motion of the object.

• Friction

: A force that resists the motion of two surfaces that are in contact with each other.

• Momentum

: The product of mass and velocity (mass ✕ velocity) for an object.

• Oscillation

: A repetitive cycle or change between two or more different states or positions.

• Pendulum

: An object hung from a fixed point that swings back and forth due to the force of gravity, until friction slows it down and eventually causing it to stop swinging.

• Period

: The time required to complete 1 whole cycle or oscillation.

• Velocity

: The rate of change of position over time.

## Learning outcomes

Al completar este experimento, los alumnos serán capaces de:

• Describir el movimiento de un péndulo.
• Medir el periodo y la frecuencia de un péndulo.
• Visualizar la aceleración de un péndulo a través de su movimiento.
• Identificar las fuerzas que actúan en un péndulo.
• Explorar los efectos de la longitud de un péndulo en su periodo de oscilación.
• Investigar la influencia de la resistencia del aire en el movimiento de un péndulo.

## Did you know that?

The first swing ride was invented in Oklahoma in the 1890s and it was initially called “The Ocean Wave”. A Pirate Ship or Galleon is an amusement park ride consisting of a swinging ship, where riders can experience different levels of angular momentum. There is also a manually-operated variant where riders have to pull on ropes to make the ship swing, these are called: swing boats.

Why are riders not thrown out of the ride as it swings? The motion of the ride creates a force that pushes the riders towards the equilibrium position. In addition, the arc of the ride generates a centrifugal force, which works similarly to the Gravitron ride.

## Background

Pendulums, or pendula, were first used in ancient China to detect earthquakes. A distant tremor would cause the pendulum to sway, revealing the direction and force of the earthquake.

Italian scientist Galileo Galilei was the first to study the properties of pendulums, beginning around 1602. He discovered that pendulums made useful timekeepers due to a phenomenon called isochronism. He was the first to record the time of motion of objects! Today, we know that the pendulum motion is a special type of oscillation motion caused by gravity and air resistance, and is studied in a branch of physics called Classical Mechanics.

In this activity, we will explore pendulum motion by measuring the acceleration of an object fixed to the end of an oscillating pendulum. We will analyze oscillation data, such as the period, frequency and amplitude, to find out how pendulums of different lengths behave. We will also consider the forces that act on a pendulum during motion.

## Sensor Setup

The sensor we are using for this experiment is already attached to the surface of the board (IMU), and no extra sensors will need to be set up.

## Physical Setup

Captain’s Warning: if you are powering the board using the USB cable, the cable may affect the ship’s swinging. Do you know why?

## Collecting Data

1. Open the Science Journal.
2. Start a new experiment.
3. Select the sensor icon in the bottom tool drawer, and select the Y accelerometer.
4. Hold the Arduino Science Carrier Board pendulum at a 10 degrees angle using your protractor.
5. Tap “start recording”.
6. Let go of the Arduino Science Carrier Board! Allow the pendulum to oscillate back and forth until it comes to a complete stop.
7. Tap “stop recording”.
8. Change the title of the recording to “Short Pendulum”.
9. Your graph should show oscillations as your pendulum swings back and forth. Find two peaks that are next to each other, and drag the cursor along the graph to measure the time between the two peaks. This time difference between the two neighboring peaks is equal to the half of the period of oscillation. Calculate the period using the formula
10. period = 2 ✕ time difference between the two neighboring peaks.
11. Measure and record the time it takes for the ride to come to a complete stop.
12. To test the period of oscillation for a longer pendulum, tie your longer string and attach it to the ruler in the same way you did previously, and repeat steps 5 - 9 in this section.

## Results and Analysis

• What is the effect of pendulum length of period of oscillation?
• Plot a scatter graph of period (y-axis) versus length (x-axis) with curve of best fit.
• If the length of the pendulum is doubled, does the period also double?
• Does the amplitude of the pendulum change over time? Why?
• Does the period of the pendulum change over time? Why?
• Does the frequency of the pendulum change over time? Why?
• What forces act on a pendulum in motion as it swings?
• Use the raw data graph in Science Journal that shows pendulum acceleration over time, to find the position of the pendulum when its acceleration is highest, zero and lowest.
• Since acceleration is directly related to force, find the position of the pendulum when the force acting on the pendulum is highest, zero and lowest.
• What are some common uses for pendulums?

## Future directions, next steps

• Add mass to the board by adding the standoffs. How does the mass of the pendulum affect its motion?
• Vary the initial position (angle) of the pendulum before release, and measure the period of oscillation of the pendulum. How does the initial position affect the period?
• Add a cardboard sail to the pendulum to introduce air resistance. Investigate the influence of the sail on the period of the pendulum and time it takes for the ride to come to a complete stop.