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Purpose:
You might think that if you spin a mass on a string that the tension
in the string will double if you double the speed of spin but
this is not the case. Using common materials you will verify the
relationship between velocity and centripetal force
Materials/Setup:
Procedure:
- Adjust the tape marker so that the radius of the fish string
(r) is exactly .5 m
- Carefully spin "m" faster and faster as Fw raises
until the tape market almost touches the tube, keeping the velocity
(v) constant
- Watch the second hand of a clock and count the number of spins
in 20 seconds
- Record the number of spins
- Do this for 2 , 3 , and 4 washers
Data:
| Fw (Fc) |
spins in 20 sec |
(v)elocity
spins x  / 20 |
Velocity increase factor |
| 1 washer |
_____ |
v1=_____m/s |
| 2 x washer |
_____ |
v2=_____m/s |
v2/v1=_____ |
| 3 x washer |
_____ |
v3=_____m/s |
v3/v1=_____ |
| 4 x washer |
_____ |
v4=_____m/s |
v4/v1=_____ |
Analysis:
- Having kept the spinning mass (m) constant and the radius
constant, what does your data show you between velocity and
centripetal force?
- What does the equation Fc=mv²/r tell
you about the Fc as you increase the v?
- What factor would you have to increase "v" to
levitate 9 washers
Conclusion:
Finally, include a short descriptive summary, all data, calculations,
conclusions and turn in to the instructor.
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