Angular Momentum Chair: Difference between revisions
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== Why This Works == | == Why This Works == | ||
===Short Explanation=== | |||
Momentum is when something with mass has a velocity to it. A simple example of this is walking across the floor; when walking at a constant pace, you have momentum. Angular momentum is when you have a mass with velocity, but it is either spinning or moving on a curve. an example would be the feeling you get when you are in a car that goes quickly around a turn. You have momentum while in the car, and when it is turning that momentum is angled. So, you feel what you might think of as a "pull" away from the inside of the turn. This is because momentum is conserved, meaning that it stays at the same amount at all times. | |||
When the volunteer was spinning with the weights held out, the weights had angular momentum to them, and we can think of them drawing a big circle around the volunteer. When they pulled the weights in, the weights now made a smaller circle. If they stayed spinning at the same initial rate, then the weights would be moving much slower in that smaller circle, which would mean that they lost momentum. So in order for momentum to be conserved, the chair started spinning faster! This is true for the opposite as well: When they move the weights outward, they start making a big circle again, so momentum is conserved by them slowing down. | |||
The wheel also uses this idea. When the wheel is spinning vertically, it has momentum along that vertical line. When they turn the wheel sideways, it loses some momentum while changing to the horizontal line, and that momentum goes into the volunteer. Since they are sitting on the stool, the stool will start to spin! The direction they spin in is related to the direction that the wheel is spinning. This means that, if you took the wheel, turned it around, and gave it back, that they would then spin in the opposite direction when they turn it! | |||
===Full Explanation=== | |||
Momentum is when a mass has a constant velocity, meaning that it has zero acceleration. This type of momentum we can think of being linear, or traveling along a single dimensional line. When an object is changing the direction of its velocity, it will experience '''''Angular Momentum'''''. This introduces a second, directional variable, which changes in relation to the velocity variable. Angular Momentum can '''''also''''' be seen in a third dimensional view, where the change in direction In other words: | |||
{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:center" | |||
| Linear Momentum | |||
| Angular Momentum (two-dimensional) | |||
|- | |||
| Grade Range: | |||
| [[Elementary School]], [[Middle School]], [[High School]] | |||
|- | |||
| Format: | |||
| [[Hands-on]], [[Stage]] | |||
|} | |||
== Additional Information == | == Additional Information == | ||
Revision as of 21:50, 14 October 2015
| Physics, Astronomy: | Momentum, Angular Momentum |
| Grade Range: | Elementary School, Middle School, High School |
| Format: | Hands-on, Stage |
This demonstration is versatile, and is flexible enough to fit into almost any Physics or Astronomy themed show. The topic matter is simple enough for young kids to understand, and it can be applied to much that older students would be learning in class.
Materials
- Hand Weights
- Bike Wheel
- Spinning Stool
Safety Precautions
Please read the Physical Demonstration section of the Demonstration Safety page before performing this demonstration.
Demonstration
- Choose a volunteer from the audience to come and sit on the stool, with their feet on the bar. Give them the hand weights, and instruct them to hold the weights out sideways. Then, after you start spinning them, they are to pull the weights in when you say "GO". Perform the demonstration.
- Now have them do it again, but this time have them start with the weights held to their chest, and on "GO" they extend their arms outward. Thank them for volunteering and have them return to their seat. Explain the first part of the demonstration at this time.
- Choose a new volunteer, someone who can hold the wheel up and away from themselves without the wheel hitting them. Have them sit on the stool, with their feet on the bar, and give them the wheel. Have them try to turn it on its side, to see if they can hold it Point out that, right now, nothing happens when they do that.
- Take the wheel back, and get it spinning quickly. Hand it back to the volunteer and have them turn it on its side again. They will start to spin!
- Thank the volunteer, and have them return to their seat. Explain the demonstration.
Why This Works
Short Explanation
Momentum is when something with mass has a velocity to it. A simple example of this is walking across the floor; when walking at a constant pace, you have momentum. Angular momentum is when you have a mass with velocity, but it is either spinning or moving on a curve. an example would be the feeling you get when you are in a car that goes quickly around a turn. You have momentum while in the car, and when it is turning that momentum is angled. So, you feel what you might think of as a "pull" away from the inside of the turn. This is because momentum is conserved, meaning that it stays at the same amount at all times.
When the volunteer was spinning with the weights held out, the weights had angular momentum to them, and we can think of them drawing a big circle around the volunteer. When they pulled the weights in, the weights now made a smaller circle. If they stayed spinning at the same initial rate, then the weights would be moving much slower in that smaller circle, which would mean that they lost momentum. So in order for momentum to be conserved, the chair started spinning faster! This is true for the opposite as well: When they move the weights outward, they start making a big circle again, so momentum is conserved by them slowing down.
The wheel also uses this idea. When the wheel is spinning vertically, it has momentum along that vertical line. When they turn the wheel sideways, it loses some momentum while changing to the horizontal line, and that momentum goes into the volunteer. Since they are sitting on the stool, the stool will start to spin! The direction they spin in is related to the direction that the wheel is spinning. This means that, if you took the wheel, turned it around, and gave it back, that they would then spin in the opposite direction when they turn it!
Full Explanation
Momentum is when a mass has a constant velocity, meaning that it has zero acceleration. This type of momentum we can think of being linear, or traveling along a single dimensional line. When an object is changing the direction of its velocity, it will experience Angular Momentum. This introduces a second, directional variable, which changes in relation to the velocity variable. Angular Momentum can also be seen in a third dimensional view, where the change in direction In other words:
| Linear Momentum | Angular Momentum (two-dimensional) |
| Grade Range: | Elementary School, Middle School, High School |
| Format: | Hands-on, Stage |
Additional Information
- Make sure to reference real-life examples of this concept in use, such as figure skating, planetary orbits, the length of the day, or spinning tops!
- This demonstration is a part of the Astronomy Show.