Lesson D7: Applying Pressure

Key Ideas     Unit Checklist

  Video Lesson

How does pressure transfer force in hydraulic and pneumatic systems? Watch this video to learn more. 

 
 

  Lesson D7: Applying Pressure


Figure D.2.7.1 – In theatres, orchestra pits are located in front of the stage.

Figure D.2.7.2 – Hydraulic machines raise and lower orchestra pits.


Figure D.2.7.3 – Cameras to capture stage performances are often controlled using hydraulics.
Reading and Materials for This Lesson

Science in Action 8
Reading: Pages 293 – 295

Materials:
4 plastic syringes (can find at a pet store, hardware store, or pharmacy), plastic tubing (3.5 m, fits snugly over syringe tips), piece of heavy cardboard (10 cm by 10 cm), plastic or styrofoam cup, tape (packing or duct), measuring cup with spout, water, large bowl, coins (100), popsicle sticks, cardboard, hot glue gun, scissors, rubber bands, pipe cleaners, paper, pencil.

Theatre Hydraulics

Theatres use hydraulic systems to create special stage effects. Hydraulic lifts raise and lower performers. Some stages contain trap doors connected to hydraulic lifts. These machines allow a performer to make a dramatic entrance out of the floor onto the stage.

An orchestra pit is located at the front of many theatre stages. An orchestra pit is a large section of stage connected to a hydraulic system. This section of stage can be raised and lowered. Orchestra pits are used in performances that have live accompanying music, like opera and ballet. Musicians sitting in the lowered orchestra pit are hidden, so that the audience can clearly see the main stage performance.

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Examples of Theatre Hydraulics

Cirque du Soleil is a theatre company known for their innovative live shows. Watch this video to see how hydraulics make a Cirque du Soleil stage tilt dramatically.

 
 
 
 
Watch these videos to learn about the hydraulic machines that can be found in most large theatres.

 
 
 
 
 
 

  Try It! 

Build a Hydraulic Jack

Try this experiment to build a simple hydraulic jack.

Materials: 
  • 2 plastic syringes (can find at a pet store, hardware store, or pharmacy)
  • Plastic tubing (about 30 cm, fits snugly over syringe tips)
  • Piece of heavy cardboard (10 cm by 10 cm)
  • Plastic or styrofoam cup
  • Packing tape or duct tape
  • Measuring cup with spout
  • Water
  • Large bowl
  • Coins (100)

Instructions:

  1. Tape both syringes, nozzles facing down, securely to the side of a counter or tabletop. The syringes should be about 20 cm apart.

  2. Remove the plungers from both syringes.

  3. Connect the syringe nozzles with the plastic tubing. Wrap the connections with tape so that they cannot leak.

  4. Fill the measuring cup with water.

  5. Slowly pour water into one syringe until both syringes and the plastic tubing are full.

  6. Hold the large bowl underneath the syringes to catch any drips. Carefully replace a plunger into the top of one syringe and slowly push it all the way down.

  7. Replace the plunger in the other syringe. Push the plunger halfway down the syringe.

  8. Tape the piece of cardboard to the top of one plunger.

  9. Tape the bottom of the plastic cup on top of the piece of cardboard.

  10. Place 20 coins into the plastic cup.

  11. Push down on the other syringe. Can you lift the coins?

  12. Keep adding more coins to the plastic cup, 20 at a time. Test the hydraulic lift each time you add more coins. How many coins can you add, before they are difficult to lift?

  13. Watch this video to see a similar experiment of a syringe hydraulic lift.

 
 

Question: 

Think about the following question very carefully. Then, type or write your answer. After you have your answer, click the question for feedback.

Large hydraulic machines use engines powered by electricity or gasoline. Engines spin and create motion, which applies force to the hydraulic system.
Figure D.2.7.4 – A hydraulic motor makes a ferris wheel turn.
Figure D.2.7.5 – Amusement park rides use hydraulic and pneumatic systems.

Amusement Park Hydraulics and Pneumatics

Amusement park rides use hydraulic and pneumatic systems for safety, for moving and for braking. For example, Ferris wheels are powered by hydraulic motors. Hydraulic motors create the large rotating force that is needed to turn the Ferris wheel. Rollercoasters use pneumatic systems to control the restraint bars that prevent people from falling out. Pneumatic brakes slow down many amusement park rides.

Some amusement parks have virtual reality rides that simulate risky activities. On these rides, people sit in chairs and watch a screen. The chairs in virtual reality rides are controlled by hydraulics. This makes the chairs move in a direction that corresponds to the motion on screen.

Figure D.2.7.6 – Hydraulics can be seen all over the amusement park if you look closely. Photo courtesy Baer Tierkel.
Figure D.2.7.7 – Even gentle rides for children use hydraulics. Photo courtesy Larry Pieniazek.

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Ferris Wheel

Watch this video to learn more about the invention of the Ferris wheel.

 
 
Figure D.2.7.8 – Flight simulator machines tilt and move like a real airplane.
Figure D.2.7.9 – Flight simulator machines train pilots.


Figure D.2.7.10 – Flight simulators are like realistic video games.
Hydraulic Simulators

Airplane pilots use flight simulators to learn how to fly in different situations. A flight simulator allows pilots to learn how to fly in dangerous situations, without being at risk of crashing a real airplane. Early flight simulators did not move, and only had airplane cockpit control levers and buttons.

In the 1970’s, as computer graphics improved, screens were added to flight simulators. Another innovation was connecting the body of the flight simulator to a moving platform that could tilt in all directions. This simulates the real motion of an airplane. These platforms are controlled by hydraulic systems that connect to levers and buttons in the cockpit.

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Flight Simulator

Watch this video to see how hydraulics make a flight simulator move.

 
 

  Try It! 

Design a Pneumatic Arm

Try this activity to design and build a working pneumatic arm. 

Materials: 
  • 4 plastic syringes (can find at a pet store, hardware store, or pharmacy)
  • Plastic tubing (3 m, fits snugly over syringe tips)
  • Popsicle sticks
  • Cardboard
  • Hot glue gun
  • Tape
  • Scissors
  • Rubber bands
  • Pipe cleaners
  • Any other useful materials
  • Paper
  • Pencil

This activity involves a hot glue gun. It must be completed with the supervision of an adult. DO NOT attempt this activity by yourself.

Hot glue guns can burn you or others if you are not careful.
Never leave a hot glue gun unattended.
Unplug the glue gun when you are done.
Allow the hot glue gun to cool in a safe place after use.

Take care with scissors; don't cut yourself or anyone else!
Instructions:

  1. Draw a design for a pneumatic arm that can move up and down. Here are some things to consider as you develop your design:

    • You can use any or all of the listed materials.
    • You can be creative and make your arm do more than just move up and down. For example, can you make a pneumatic claw?
    • Where on the arm does force needs to be applied, to make the arm move up and down? A syringe plunger needs to be placed at this location.
    • Watch the following videos for inspiration.

 
 
 
 
 

 

  1. Build and test your pneumatic arm. The process to build a working pneumatic arm will probably involve some trial and error. If your pneumatic arm doesn’t work the first time, think about what you can change to make it work better. Change the structure and test it again.

Sharing:

Congratulations on completing the activities in this lesson! Consider sharing your hydraulic jack and/or pneumatic arm in the course Sharing Forum! Take a photo or video of your creations and post them; your teacher and other students would be interested in seeing how your hydraulic and/or pneumatic arm turned out!



  Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to guide your learning.

Unit D Lesson 7 Self-Check

Instructions


Complete the following 6 steps. Don't skip steps – if you do them in order, you will confirm your understanding of this lesson and create a study bank for the future.

  1. DOWNLOAD the self-check quiz by clicking here.

  2. ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.

  3. COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.

  4. REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.

  5. SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.

  6. CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!

Be a Self-Check

Superhero!



Self-Check Quiz Answers

Click each of the suggested answers below, and carefully compare your answers to the suggested answers.

If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.

Garbage dumpsters are very heavy and require a lot of force to lift. A hydraulic system is able to transfer a large amount of force to a lever, to lift a heavy object like a garbage dumpster. Hydraulic levers greatly reduce the effort for humans in lifting heavy objects.
The ride contains multiple hydraulic pistons and hoses. To make the ride tilt, more force is applied to hydraulic pistons on one side of the ride compared to the other side. The side with more applied force lifts higher than that other side, which tilts the ride.
Liquid in a hydraulic system compresses less than air in a pneumatic system. As a result, liquid hydraulic systems remain at a steady pressure. With heavy loads, the pressure stays constant, so the transferred force can reliably lift the load without failing.
Heavy vehicles travelling at fast speeds are more difficult to stop than smaller vehicles. Air brakes are used on heavier vehicles because if an air brake line leaks, it still contains some air and can still make the air brake work. Minor leaks do not cause air brakes to fail. However, if a hydraulic brake line leaks, the brakes stop working, which prevents the vehicle from stopping.
Wheels required the effort of people or animals to transfer force to the wheel and the crane. Hydraulic systems can transfer much larger forces to the crane through a fluid.