| As The World Turns |
| Grades 5-6 |
Lesson #14 |
| Modifications to Video |
There have been several changes to the lesson plan since the video was made. This lesson plan reflects the latest changes made as a result of suggestions from teachers who have presented the lesson during the daytime program. Please continue to send us your ideas! |
| |
Click here to view As the World Turns Video |
| Educational Objective |
To directly experience the effects of gravity and centrifugal force |
| Materials List |
- - Bicycle wheel gyroscope
- - Handle with cable and hook for bicycle wheel
- - Centrifugal hoops on motor stand
- - Large gyroscope
- 15 - Small gyroscopes
- - Rotating lab stool
- - globe
- 3 - Knee-high stockings with tennis balls inside
- - Centrifugal force demonstrator - Bucket (4 qt)
- - Centrifugal force demonstrator - 2-liter bottle
- - Drill with mounted wheel
- - Extension cord
- - Board for stopping bicycle wheel
|
| |
View lesson on separate page |
| |
Lesson |
| Place the drill mounted |
Place the drill mounted wheel against the large metal gyroscope wheel. Carefully start the gyroscope spinning and run it up to high speed. Set the drill down and gently turn the gyroscope with its handle either clockwise or counter clockwise. What happens? One end of the gyroscope axis will lift up into the air. Caution: The heavy wheel can jump completely out of the base and injure hands. Make sure both sides of the Gyroscope are securely in place before moving the handle.
|
| You may also carefully lift |
You may also carefully lift one end of the gyroscope up and then let go and observe what happens.
|
| |
|
| Have a student drop |
Have a student drop a tennis ball to demonstrate that we have a force of gravity pulling toward the center of the earth.
|
| Spin centrifugal hoops |
Spin centrifugal hoops (metal loops on shaft): This demonstrates gravity pulling in the North and South poles and centrifugal forces pushing at the equator areas. Centrifugal force is the outward force that comes about in a rotating system, which points away from the center of rotation. Caution: do not turn speed knob above 60.
|
| Show students the globe |
Show students the globe and ask if after seeing the centrifugal hoops they think that the earth is a perfect sphere.
|
| Swing the centrifugal |
Swing the centrifugal force demonstrator (2 liter bottle with colored water)in a windmill fashion to show centrifugal force overcoming gravitational force. Allow students to experiment with this, and with a bucket of water.
|
| |
 |
| Have a student swing |
Have a student swing a ball in a stocking around his or her head. The faster he or she rotates the ball the farther out the ball will be. What happens if you stop rotating the ball and let it wrap around your arm? The ball twirls faster and faster till it's completely wrapped around your arm. This is due to the principle of Angular Momentum (A), the force of a rotating object. A=mvr. If we solve for v, then v=A/mr. We can see that as r becomes smaller, velocity becomes faster.
|
| |
 |
| Have a student hold the bicycle |
Have a student hold the bicycle gyroscope at arm's length by the axle handles. Caution students not to let the spinning wheel touch their body. Use the drill to set the wheel spinning. It will tend to veer a certain direction and resist the opposite direction. This effect will be pronounced if the student attempts to move the wheel around. Then have them hold only the cable attached to one of the axle hubs. If the wheel is spinning fast enough, it will stay upright. This principle is used in large ships to keep them upright in storms.
|
| |
|
| Have a student hold the spinning |
Have a student hold the spinning bicycle gyroscope while sitting on the rotating lab stool. He or she will notice further the dynamics of gyroscope forces as the stool will be forced to rotate when the gyroscope is tilted from side to side. Caution students to hold the wheel away from their body and use the brown board (placed on the floor) to stop the wheel when they are done.
|
| |
|
| Allow the students |
Allow the students to experiment with the student gyroscopes. Please have them work in pairs on the floor as the gyroscopes break very easily.
|
| Call attention to |
Call attention to the career fields that are related to this module. Discuss how students might prepare for occupations that interest them.
|
| |
End of Lesson |
| |
Safety precautions: Be very careful with the bicycle gyroscope so that students do not get their fingers or clothing caught in the spokes. Make sure students hold the gyroscope firmly and keep it away from the body.The cable should only be attached to the hub when it is used to hold the wheel. It could get caught in the spokes if left dangling. Choose students that have plenty of reach. Hold tightly while spinning. Teacher should stand facing the student prepared to lift the gyroscope with both hands if a student has difficulty maintaining control. To stop the gyroscope, bend forward with arms extended until the wheel brakes itself on the floor. |
| Definitions |
- Centripetal force
is the force that compels a body to move in a circular path. According to the law of inertia, in the absence of forces, an object moves in a straight line at a constant speed. An outside force must act on an object to make it move in a curved path. When you whirl a stone around on a string, you must pull on the string to keep the stone from flying off in a straight line. The force the string applies to the object is the centripetal force. The word centripetal is from two Latin words meaning to seek the center. |
| |
Centripetal force acts in other ways as well. For example, a speeding automobile tends to move in a straight line. Centripetal force must act on the car to make it travel around a curve. This force comes from the friction between the tires and the pavement. If the pavement is wet or icy, this frictional force is reduced. The car may then skid off the road because there is not enough centripetal force to keep it moving in a curved path. |
| |
You can use the following formulate to calculate the centripetal force (F) necessary to make an object travel in a circular path: |
| |
 |
| |
- Gyroscope inertia
-
is the tendency of a spinning body to resist change in the direction of its axis. Inertia keeps the axis of a spinning top straight up until the top slows. Use the Right Hand Rule. Form your RIGHT hand in the "hitch hiker" mode. The fingers represent the spin direction of the wheel, and the thumb represents the directional force of the gyroscope axis.
|
| |
- Angular Momentum
-
(A) is the force of a rotating object. A=mvr (m=mass, v=velocity, r=radius).
|
| |
- Centrifugal force
-
is the force arising in a rotating reference system. It points away from the center, in the direction opposite to the centripetal force.
|
| |
- Centripetal force
-
is the force that causes an object to change direction. For uniform circular motion, the force is directed toward the center of the circle and has a magnitude given by mv2/r.
|
| This lesson relates to the following |
Career Fields
Science, Technical
Occupations
- Aeronautical Engineer:They design, construct, and test aircraft, missiles, and spacecraft. They might also conduct basic and applied research to evaluate adaptability of materials and equipment to aircraft design and manufacture. They also may assist in planning the technical phases of aircraft systems, flight operations, and logistics. Education: Bachelor's Degree
- Physicist: They explore and identify basic principles governing the structure and behavior of matter, the generation and transfer of energy, and the interaction of matter and energy. Some use these principles in theoretical areas, such as the nature of time and the origin of the universe; others apply their physics knowledge to practical areas such as the development of advanced materials, electronic and optical devices, and medical equipment. They design and perform experiments with lasers, cyclotrons, telescopes, mass spectrometers, and other equipment. They attempt to discover laws that describe the forces of nature, such as gravity, electromagnetism, and nuclear interactions. They also find ways to apply physical laws and theories to problems in nuclear energy, electronics, optics, materials, communications, aerospace technology, navigation equipment, and medical instrumentation. Education: Doctor of Philosophy
|
| Review Questions |
- Due to Earth's rotation our planet is not a perfect sphere. What force alters our planets shape? (demonstrated by the hoops on motor stand.)
- When spinning the bucket what force keeps the water in the bucket?
- When swinging the tennis ball in the stocking what forces are acting on the stocking?
- What is the difference between centrifugal and centripetal forces?
- How is a bicycle like a gyroscope?
|
| Top of Page |
|
