Section 1: Experiment and Observation
.
A. Objective
To calculate the angular velocity of a spinning object using varying hanging and rotational masses and varying radii
To calculate the theoretical centripetal force
To calculate the experimental centripetal force
To analyze the experimental data
B. Materials and Equipment
1 assistant
1 safety goggle
1 Centripetal force apparatus to include: a glass rod, steel washers (20), paper clips (2), Rubber stopper 2 Hole, Thread (4 m)
1 Scale spring 500 g
1 stopwatch-digital
1 tape measure, 3 m
Photo of myself and all the equipment used for the lab, along with my student information card
C. Data
Variable Radius
Procedure: The number of washers was recorded from the lab kit as well as the mass of the rubber stopper, mass of the washers combined and the mass of each washer in Data Table 1.
Next the centripetal apparatus was assembled per the instructions.
Data Table 2: Varying radius data
Photo of the fully assembled centripetal force apparatus, along with my student information card
A
B
C =B/10
D = 2xA
E =D/C
F = E2
Radius (m)
Time (s)
10 rev
Time (s)
1 rev
Circumference
2r (m)
Velocity
()
(Velocity)2
()
Trial 1
0.7
4.8
0.48
2.5
5.2
27.04
Trial 2
0.6
5.2
0.52
3.14
6.0
36
Trial 3
0.5
5.4
0.54
3.76
6.98
48.72
Trial 4
0.4
5.7
0.57
4.39
7.7
59.29
Constant hanging mass (approximately 30 g): 0.0258 (kg)
Constant rotating mass: Use mass of stopper from Data Table 1: 0.0171 (kg)
The centripetal apparatus was used to swing the stopper in a circular motion. The hanging mass was slowly released to adjust the rotation speed of the stopper until the paper clip below the glass tube is stable a few centimeters under the glass tube. The spinning was stopped and the measuring tape was used to measure the length of the string in meters. This length was recorded as the radius for trial 1 in Data Table 2. Next my lab partner Laura Davis, used a stopwatch to time (in seconds) 10 revolutions at this stable rate. This was recorded in Data Table 2 under Trial 1. The length of the string was then shortened between the stopper and the top of the glass tube by 10 cm. The new length was measured by the tape measure and recorded as the radius for Trial 2 in Data Table 2. This 10 cm increment was used for the subsequent trials and recorded accordingly in Data Table 2.
Fixed Radius-Varying Hanging Mass
Procedure:
We will look at how mass affect centripetal force. We will keep the radius constant at 0.5 m while the hanging mass will subsequently increase. This data will be recorded in Data Table 3.
Constant rotating mass: Use mass of stopper from Data Table 1: 0.0171 (kg)
Data Table 3: Varying hanging mass data
A
B
C =B/10
D = 2xA
E =D/C
F = E2
Hanging mass (kg)
Radius (m)
Time (s)
10 rev
Time (s)
1 rev
Circumference
2r (m)
Velocity
()
(Velocity)2
()
Trial 1
0.045
0.5
5.2
0.52
3.14
6.04
36.48
Trial 2
0.057
0.5
4.8
0.48
3.14
6.54
42.77
Trial 3
0.062
0.5
4.5
0.45
3.14
6.97
48.58
Fixed Radius-Varying Rotating Mass
Procedure:
We will now look at how mass affect centripetal force. The radius will be a constant while the rotating mass increases. The rotating mass was done with a trial of 10 revolutions and two washers added to the rotation for subsequent trials. These results are summarized in Data Table 4 below.
Constant hanging mass: 0.058 kg
Data Table 4: Varying rotating mass data
