1. Tagging Great White Sharks, Parts 1 & 2
OCEARCH Physics Part 2
Tagging Great White Sharks, Parts 1 & 2

2. Introduction
The M/V OCEARCH is a 126 foot vessel equipped with a hydraulic platform to conduct scientific research.
This special ship allows researchers to capture, tag, and collect data from great white sharks before they are released back to the ocean.
Photo: The M/V OCEARCH – at sea laboratory and mother ship for OCEARCH.

3. Introduction Each great white shark is tagged with:
SPOT tag (smart position and temperature tag)
PAT tag (pop-up archival tag) not shown
Accelerometer

4. SPOT Tags
A SPOT tag regularly sends signals to satellites using powerful transmitters every time a shark swims to the surface.
The SPOT tag starts recording data, such as temperature of the water, depth the shark is swimming, and salinity immediately after the shark is released back to the ocean.

5. SPOT Tags
The tag also records a “ping” or landmark on a map that gives the geographic location of the shark.
This tag allows you to track sharks in near-real time on the Global Shark Tracker™. No other tag gives data in “near-real time”.

6. PAT Tags
A PAT tag is used to collect data such as water temperature, light, and the shark’s swimming depth.
The tag is designed to detach from the shark after several months.
Once retrieved from the water, scientists can then collect the data stored on the tag.

7. Accelerometer
An accelerometer records the speed the shark swims every second.
This allows the researchers to monitor the shark’s behavior immediately after release.
The data from this tag cannot be collected until the tag detaches from the shark.

8. Questions?

9. Tagging Great White Sharks, Part 3
OCEARCH Physics Part 2
Tagging Great White Sharks, Part 3

10. How do satellites work?
The time it takes for a satellite to complete one full orbit around Earth is called its orbital period.
A satellite must travel at a certain radius and period in order to maintain its orbit, thus collecting and relaying important data to the marine researchers.
Some satellites must stay “stationary” over a point on Earth and therefore must orbit at the same rate the planet turns. This is how most communications and GPS satellites operate.
So it is very important to know how to calculate the forces that keep a satellite in orbit.
Satellites are objects that revolve around the planet in a circular path, called an orbit. Satellites used to be objects of great mystery, only used for secret military purposes. But now, satellites make up a very large part of the average American’s life. Because of satellites, we can watch television, predict the weather, make phone calls, browse the internet, and navigate using a GPS device. For OCEARCH, satellites allow the researchers to collect precise data in order to learn more about great white sharks.

11. Acceleration Velocity
The rate of change of velocity.
Velocity
The rate and direction of motion.
The acceleration of an object is dependent upon velocity change.
The acceleration is always in the direction of the velocity change.
If there is no change in velocity, then no acceleration can occur!

12. Acceleration and Velocity
If an object is moving to the right with a velocity of m/s (meters per second) and continues to move at 3 m/s, is the object accelerating?
3 m/s 3 m/s The object is not accelerating because there is no change in velocity.

13. Acceleration and Velocity
If an object is moving to the right with a velocity of 10 m/s and then increases to 20 m/s, is the object accelerating?
10 m/s 20 m/s The object is accelerating because there is a change in velocity.

14. Acceleration and Velocity
If an object is moving to the right with a velocity of 30 m/s and then decreases to 25 m/s, is the object accelerating?
30 m/s 25 m/s The object is accelerating because there is a change in velocity, even though it is decreasing.

15. Centripetal Force
Centripetal force is the force that causes an objects to move in a circular motion.
An object moving in a circle is ALWAYS accelerating.
An object accelerates when its velocity changes. And velocity is defined by rate AND direction. So if an object is moving in a circular motion, its direction is constantly changing. Therefore its velocity is changing and the object is accelerating.
Teacher Demonstration – Centripetal Force (5 minutes)
Have you ever wondered how a satellite stays up, instead of falls down, as it orbits the Earth? Here's an experiment to show students the different forces that keep satellites revolving around us.
Materials – Ping pong ball and a rubber band.
First, cut the rubber band so that it is one long piece. Tape one end of it to the ping pong ball.
Holding on to the loose end of the rubber band, slowly swing the ping pong ball in a circular motion.
Now increase the speed of the circular swing, noting the distance the ping pong ball moves from your hand.
What happened? Did the ball revolve farther away from you when the speed was increased?
But as long as you hold on to one end of the rubber band, and the tape stays stuck, the ball won't revolve any further away after a certain point. The stretchiness of the rubber band is maxed out. But the ball won't come any closer either if you maintain your velocity. This shows the balance between the force of gravity, which tends to pull the ball toward the Earth (your hand), and the centripetal force, which forces the ball away. That's how satellites work! They revolve around the Earth "stuck" between the two forces, gravitational and centripetal. The satellites are free to fly around the Earth instead of falling down, but not SO free that they revolve away into space.

16. Calculating Centripetal Force
The formula used to calculate centripetal force is:
Fnet is the net (total) centripetal force acting on the moving object, causing it to travel in a circular motion.
Fnet =
V is the velocity/speed of the moving object.
m is the mass of the moving object.
R is the radius of the moving object.
Scientists use this equation to determine the centripetal force acting upon objects, such as satellites. This allows them to control the satellites and keep them moving at the right velocity, otherwise the satellite would fall from space or float off into space.

17. Calculating Centripetal Force
If a satellite is orbiting around the Earth at a velocity of 700 m/s, what is the net centripetal force acting on the satellite? The mass of the satellite is 400 kg and the radius of the satellite is 900 m.
Fnet =
Fnet =
N stands for Newton, which is the metric unit used to measure forces such as centripetal force. One Newton is the force required to accelerate a mass of one kilogram at the rate of one meter per second every second. It is named after Sir Isaac Newton, a famous physicist.

18. Calculating Centripetal Force
If a satellite is orbiting around the Earth at a velocity of 350 m/s, what is the net centripetal force acting on the satellite? The mass of the satellite is 210 kg and the radius of the satellite is 100 m.
Fnet =
Fnet =

19. Review
Every time an OCEARCH shark’s dorsal fin breaks the surface of the water, its SPOT tag sends a signal to overhead satellites.
The satellites process the signal, determine the shark’s location using the Doppler Effect, and relay the data to the Global Shark Tracker™.
Centripetal force is the force that causes an object to move in a circular motion, such as a satellite orbiting around the Earth.
If an object is moving in a circle, it is constantly changing direction. Therefore, its velocity is changing and the object is accelerating.
It is important for physicists to know how to calculate centripetal force. This allows them to control the satellites and keep them moving at the correct velocity, otherwise the satellite would fall from space or float off into space.
If this happened, OCEARCH would not be able to receive its valuable data to research and ultimately conserve sharks!

20. Questions?

21. Tagging Great White Sharks, Parts 4 & 5
OCEARCH Physics Part 2
Tagging Great White Sharks, Parts 4 & 5

22. What information is obtained by tagging sharks?
Migratory patterns
Stage of life
Physiology and overall health
Photo: “Itabaca” a 8 ft. 2 in. tiger shark named after the canal in the Galapagos it was found in.
Long-term tagging opportunities allow scientists to monitor shark migratory patterns, which enables leaders and policy-makers to make more informed decisions when planning conservation management strategies. If we know where great white sharks hunt, breed, give birth, etc., we can protect these locations to ensure the survival of the species.
By recording stage of life (immature/mature), researchers are able to predict breeding patterns and breeding areas for great white sharks. Knowing when and where white sharks reproduce will lead to better conservation efforts to protect this endangered species.
During the tagging process, researchers take tissue samples, check for parasites, and take a blood sample from the shark. The blood sample allows the researchers to test the animal’s overall health but also allows them to monitor the animal’s stress levels.
During the tagging process, OCEARCH also measures a shark’s length and girth (the circumference of the shark at its widest point). They use length to estimate how old the shark is and use both length and girth to calculate how much the shark weighs.

23. How do researchers monitor the tagged sharks?
Once a great white shark is tagged, OCEARCH monitors the near-real time data received from the tags to determine the shark’s migratory patterns.
Each month the researchers record which sharks “reported in”, meaning a shark surfaced long enough for its tag to send a signal to a satellite to record its location. Not all sharks report in each month.

24. OCEARCH looks at the statistics of the sharks that reported in versus the sharks that did not report in. Having a visual representation of this helps the researchers understand the data.
You will notice that there is a third category called “Z-Pings” included in the report. Z-pings include sharks that have reported in, but did not surface long enough for the tag to send a signal to the satellite and obtain a location.

25. How do researchers monitor the tagged sharks?
If a shark did not report in for the month, possible reasons are investigated.
Behavioral – The shark did not swim near the surface allowing the tag to send a signal.
Biofouling – Plants, bacteria, and/or other organisms (mussels, barnacles, and algae) attach to the tag which interferes with the signal.
Tag malfunctions – Just like all technology, sometimes it just quits working.
Shark mortality – The shark died from natural causes or was caught in a net or on a long line.

26. Global Shark Tracker™
Students can track tagged great white sharks and several other species of sharks with the easy-to-use Global Shark Tracker™!
With this unique tool, students can:
- navigate the map to view different parts of the world
- choose to view all of the tagged sharks in an area
- select an individual shark and click “Where Have I Been” to view that shark’s migratory pattern
- track the location of the M/V OCEARCH vessel while on expeditions
- keep up to date with the crew with a live social media feed
- read detailed biographies of each shark, which includes information such as species, gender, stage of life, length, weight, tag date, tag location, total miles traveled, and much more!
The website is free to use and only requires an internet connection and a web browser.

27. Questions?