| Purpose: |
We are conducting this experiment to show a couple
of different methods for finding the force that is exerted upon an object.
Included are the actual rotation of the object (Centripetal Force) then
by using a combination of weights (Force of Gravity) and calculating
the magnitude. |
| |
|
| Theory: |
- As an object spins in a circular
path it tends to seek the outer reaches of the rotation. The object
is obeying Newton's Second Law as the acceleration is observed
as moving in a circular motion.
-
- The equation:
- is employed for the calculation of the acceleration
after the
- RPM's are established and the mass and radius
are measured.
-
- The Magnitude of the Centripetal Force (Fc)
can be found with the equation:
- "T" is the period of time for one
entire revolution at the known RPM.
|
| |
|
| Procedure: |
- After becoming familiar with the rotator head,
the tension spring was adjusted to 0 and recorded. Then the weight
of the mass used was noted as .152 kg.
- Next the mass was measured from it's center to
the center of the rotator head as the spring was stretched as far
as it would go within the rotator head. Then those measurements
were recorded in m (kg).
- Once secured to the motor, the head is brought
to a speed that causes the indicator to move, indicating the mass
is up to speed and at it's maximum radius and centripetal force..
The RPM's are then recorded on the chart.
- After determining the rotation was 485 RPM's, the
period (T) was calculated by dividing 60 seconds by the 485 RPM's
to find .124 seconds.
- Enough data has been collected to arrive at a value
for the centripetal force using the proper equation.
- The value found for centripetal force was 22.25
N
- Now, using the same rotator head, we suspend it
from a hanger and add enough weight to move the indicator to the
same position as it reached when rotating on the motor.
- Next, the mass of the weight hanger and the weights
are totaled and noted as M.
- To find the gravitational force the equation :
- The gravitational force in this case computed to
20.50 N
- The percent difference between Centripetal and
Gravitational Force,was found to be 8.5%.
- The discrepancies can be attributed to the failing
of the human element as well as the quality of the instruments themselves.
- Now, we set the spring to 1/2 of the setting scale
and did it all again and recorded the data.
- The centripetal force increased from 22.25 N to
24.12 N because of the increase in weight and in the case of the
rotating mass, with the adjustment spring tighter, it takes more
speed (RPM's) to cause the indicator on the rotator head to trip,
thus it results in more force.
|
| |
|
| Results: |
| 1st Test |
|
2nd Test |
|
| Spring Setting: |
0 |
Spring Setting |
10 |
| Rotator Mass m: |
.152 kg |
Rotator Mass m: |
.152 kg |
| Rotator Radius r: |
.057 m |
Rotator Radius r: |
.057 m |
| RPM: |
485 RPM's |
RPM: |
506 RPM's |
| Period T: |
.124 s |
Period T: |
.119 s |
| Centripetal Force Fc: |
22.25 N |
Centripetal Force Fc: |
24.15 N |
| Added Mass M: |
1.94 kg |
Added Mass M: |
2.20 kg |
| M + m: |
2.09 kg |
M + m: |
2.35 kg |
| Force of Gravity Fg: |
20.50 N |
Force of Gravity Fg: |
23.05 N |
| % Difference: |
8.5 % |
% Difference: |
4.8 % |
|
| |
| Conclusion: |
I enjoyed this lab. It was interesting to study motion
from this aspect because it's an area I've always been intrigued by.
For instance, as a kid I always thought the car tires were thinner when
they were spinning at highway speed. Apparently that is the case thanks
to centripetal force.This experiment has shown me the method for finding
the forces associated with that spinning tire. Thanks Fc! |
| |
Back
|
