Gyro Wheel

gyro1Gyroscopes defy human intuition, common sense, and even appear to defy gravity. You’ll find them in aircraft navigation instruments, games of Ultimate Frisbee, fast bicycles, street motorcycles, toy yo-yos, and the Hubble Space Telescope. And of course, the toy gyroscope (as shown here). Gyroscopes are used at the university level to demonstrate the principles of angular momentum, which is what we’re going to learn about here.


If you happen to have one of these toy gyroscopes, pull it out and play with it (although it’s not essential to this experiment). Notice that you can do all sorts of things with it when you spin it up, such as balance it on one finger (or even on a tight string). Wrap one end with string and hold the string vertically and you’ll find the gyro slowly rotates about the vertical string instead of flopping downward (as most objects do in Earth’s gravitational field). But why? Here’s the answer in plain English:


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Comments

29 Responses to “Gyro Wheel”
  1. kathmacgall says:

    Thanks!

  2. This is due to many factors. First, it’s important to note that the camera “sees” things drastically differently from our eyes. Even the best camera will distort what is photographed, at least to some degree. The different cameras do have an impact on different looks of continents, colors, haze, etc. Also, these images are shot from vastly different angles, through windows with different refractive index and/or curvatures, with different film or different digital equipment. Some images we see are actually stitched together from many different shots.

    So yes, there are many explanations for sizes of continents appearing to change. The most likely reason would be that the shots are taken from different angles and distances from Earth.

    I hope this helps!

  3. kathmacgall says:

    Thank you for the information!

    I was also wondering why is it that in the pictures released by NASA over the years the size of the continents appear to change. is it because they use different cameras or is it something else?

  4. Hi there,

    Earth is an oblate sphere, so it’s slightly squashed. However, to the naked eye it appears to be round in videos and photos. If you measured or used a compass, you’d discover anomalies that deviate from a perfect sphere.

    Regarding mechanical gyroscopes: they do need to maintain their orientation relative to their beginning orientation. To compensate for this, early gyroscopes required regular manual adjustments.

    I hope this helps!

  5. kathmacgall says:

    Hi Aurora!

    You mentioned that the earth is a slightly squashed sphere, my question is why all the pictures from space show the earth as a perfect sphere? At least the ones i have seen from NASA so far. why is that? Also i have been wondering how do air planes artificial (gyroscopic) horizons compensate for the curvature of the earth? Especially if there gyroscopes are mechanical and not electronic? I look forward to hearing from you!

  6. Aurora says:

    It’s funny you mention this, because I’ve looked for a replacement (it’s about 20 years old) and haven’t found one! I was thinking I could make one out of a rubbery-gel substance, but am not sure which I will try first.

  7. Christine King says:

    You showed a gyroscope with a gel center that stretched. What was it called, and where could I get one? My grandson thought that was pretty cool.

  8. Anni Killam says:

    Wanna know a fidget spinner trick? If you get one up to speed and try to tilt it, it will tilt the opposite direction in your hand in an attempt to stay vertical. (Warning: many fidget spinners contain lead and mercury which can kill you if you are around them a lot)

  9. Anni Killam says:

    I wish I was there to see that! He must have looked hilarious!

  10. Dan Archer says:

    He spun round because of gyro force

  11. Aurora says:

    Yes, the faster the wheel spins, the more stable the axis is and the harder it becomes to move in a counter-direction. Not sure what you mean by a “sweet spot”…?

  12. sheri albee says:

    So, is the spinning ability of the bike wheel how bikers can do really cool spinning wheelies? Do they find the sweet spot and use it to spin?

  13. Aurora says:

    That’s okay – science is like that. Try again!

  14. Julie Telge says:

    it didnt work, the chair moved easily, and the wheel was spinning pretty fast. 🙁

  15. Aurora says:

    Neither… the briefcase kept jerking him around – it looked so funny like he was pretending, but he really wasn’t.

  16. Christophe Landa says:

    Or did he spin? 🙂

  17. Christophe Landa says:

    Did his briefcase keep spinning around and around and around?!?! 😀

  18. Aurora says:

    You can get them at toy stores!

  19. Lorelei Grecian says:

    Where can you get gyroscopes? I think they are pretty cool 🙂

    Raena

    age 10

  20. Aurora says:

    It may… but make sure it’s spinning FAST and that your chair rotates freely (use the most low-friction chair you have – the kind that if you start spinning in it it’s hard to stop!)

  21. Caroline Wood says:

    It is not working for us. We are not able to make the chair turn. Would a bigger wheel work better?

  22. Theresa Getubig says:

    i need to get out my tools and take off that wheel

  23. Debra Thomson says:

    I bet the boss was a bit FREAKED out!

  24. Aurora says:

    Acceleration can be positive or negative, depending whether velocity is increasing or decreasing. Velocity has two components: speed and direction. When you have an object moving, you slap a coordinate system on top of it to figure out the velocity. For example: a car heading NW at 65 mph is a velocity. You know the speed (65 mph) and direction (NW). If North is the positive direction on the y-axis and East is the positive direction on the x-axis, then your velocity has x and y components and can be written as a vector.

    For an object swinging in a circle (like a bike wheel), it is constantly changing direction (although the speed may be constant). A car traveling in circles will constantly be pointing its nose from N to NE to E to SE to S to SW to W to NW to S…etc. So the car is accelerating because the velocity, which can be either speed and direction (or both, like a car getting off the freeway).

    The bike wheel case, the velocity is changing because the direction is changing, so the wheel is accelerating. The direction of the acceleration is in both the direction of the wheel’s motion (tangential acceleration = rotational acceleration x radius) and inward toward the hub (normal acceleration = rotation speed2 x radius).

    If the wheel is also slowing down, then there’s another acceleration term involved. If the wheel has a lot of inertia (resistance to motion), then you have yet another factor to add in. And if you take a walk while it’s spinning, you have to account for your own walking (which includes yet another factor). Do you see how these start to get really complicated? That’s why there’s a full year of mechanics that college students take (called Statics and Dynamics) just to understand this stuff and get practice solving these types of problems. But you don’t need to worry – here’s what you really need to understand now:

    Acceleration is negative if the change in velocity is negative, which can be either one of these: change in direction is negative on your coordinate system (which you specify when you’re doing the math part of the problem) or the speed is decreasing. Note that the acceleration could be positive for a negative velocity which is becoming less negative (e.g. speeding up).

    By the way: Scientists and engineers tend to speak about “acceleration” as meaning a change in velocity, which can be either increasing or decreasing (decelerating) – it’s the same word for both.

  25. Karen says:

    We are doing your bike wheel acceleration experiment. You mention the wheel is accelerating. We (non-science folk) tend to think that acceleration means going faster and faster. But, in the case of the wheel, am I correct that the acceleration is negative since the wheel spins slower and slower as time passes? Just want to make sure we are understanding this correctly.

  26. Rachel Moser says:

    Did it it make him spin round and around?

  27. Kim Reid Kuhn says:

    cool

  28. anastasia belliard says:

    That’s great!

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