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Topics
Points of Emphasis
Prerequisites
Lab Activities
The central intent of this lab is to provide students with the opportunity to predict the
behavior of rotating systems using their knowledge of rotational dynamics and then to check
to see if the predictions are correct.
At each individual station, the students are provided with a gyroscope, a tippy top and a
butterfly yo-yo.
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Gyroscope: Here the students start the gyroscope spinning and orient it so that
the axis of rotation is horizontal. They are then asked to apply a torque to the
gyroscope and predict how the gyro will move in response.
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Yo-yo: the students place it on a table so that the string leaves the axis of
the yo-yo from a point on the axis between the table and the center of the yo-yo. Their
goal is see what happens when the string is pulled at an angle and what happens to
the motion when the angle changes. They will see that at certain angles the
yo-yo will roll towards them, at other angles it will not roll at all and at some angles
it will roll away from them. They are asked to explain why the yo-yo behaves in this
manner.
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Tippy Top: This is more of a novelty item that they can play with and try to
explain its pedular motion
At the general station there are a rotating stool, some small barbell weights and a
weighted bicycle wheel with handles.
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Activity 1: A student sits on the rotating stool and holds the rotating
bicycle wheel so that its axis of rotation is horizantal. The student predict
what will happen when the axis of rotation is moved to the vertical plane.
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Activity 2: A student sits on the stool with arms extended and holding
small weights in each hand. He/she is then started spinning and asked to bring
his hands in towards his/her body. The students are asked to predict what the
think will happen when the arms are brought in and explain the behavior of the
rotating system.
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Activity 3: While the person is spinning in Activity 2, a stationary student
uses a stopwatch to measure the angular velocity of the student before and after
the rotating students brings the weights in toward his/her body. This data is used
to estimate the percentage change in the moment of inertia of the person and the
masses when he/she pulled in his/her hands.
The third major activity involves a merry-go-groud. In this part, the students area
asked to:
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Activity 1: Computes the average angular velocity, the average period of rotation and the angular translational
veloity.
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Activity 2: Devise a method to measure the instantaneous translational velocity and then explain
why the merry-go-round slows down in terms of Newton's first law. They are also
to estimate the magnitude of the deceleartion
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Activity 3: Next they rotate the merry-go-round using a metal bar. They are asked to note how
much effort is needed to rotate the merry-go-round when the position of the push along
the metal bar is varied from in near the axis of rotation to the far end of the poll.
away from the axis of rotation.
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Activity 4: They roll a soccer ball across the rotating merry-go-round to see how it moves.
They then are asked to expain this observation.
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Activity 5: They hang a string with a wieight attached to the other end
from a ring stand and note how it hangs when the merry-go-round is at rest and when it
is in motion.
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Activity 6: The students place weights at various places around the merry-go-round and
investigate how the position of the weights effect the forces needed to rotate the apparatus.
Course Level
Student Handouts
Equipment
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Number of set-ups available:
Per lab station:
1 tippy top
1 butterfly yo-yo
1 giant gyroscope/stand
1 string (~ 1 meter in length)
1 ball of string
1 gyroscope spinner
General class supplies:
1 rotating base
1 stoop for rotating base
2 bar bells - (5 lbs each)
2 bar bells - (3 lbs each)
1 weighted bicycle in a wooden frame
1 rotating wheel in a wooden frame
1 weighted bicycle wheel with handles and a rope attached
2 1000 kg hooked masses
miscellaneous assortment of tops
Merry-go-round station:
1 merry-go-round
1 soccer ball
2 stopwatches
1 roll of duct tape
1 meter stick
1 ball of string
1 tennis ball
2 500 gm hooked masses
1 bathroom scale
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Individual Stations
Genearl Class Supplies
Merry-Go-Round Apparatus
(Number of setups: 10)
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Notes
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