Circular Motion
Objectives: Determine relationship between linear
velocity, centripetal force and acceleration.
Equipment: stopwatch, F_{c} setup, mass set
Methods:
1.
Sketch the F_{c} setup.
Label the radius, F_{c}, mass m, reference washer,
mass holder.
2.
Measure the radius with the reference washer at its
desired position. Hang
a 50.0 g mass on the F_{c} set up.
This mass represents a force F_{c} = mv^{2}/r.
Let g = 10m/s^{2} such that a 50.0 g mass has a
weight F_{c} equal to 0.5 N.
3. Put your goggles
on now. Whirl and
time the stopper for 10 revs in a horizontal circle.
Be sure the reference washer does not move up and
down, and does not touch the handle.
4. Determine the
period T (time) for one revolution, then calculate v, and
a_{c}. The
radius remains constant in this lab.
v = 2πr/T
and a_{c}
= v^{2}/r.
5. Repeat for
various masses to get 45 trials (up to a maximum of 250 g).
Analysis:
1.
Plot graphs of:
(a)
F_{c} vs
a_{c} (a_{c} on the xaxis)
(b)
v^{2} vs a_{c}
(a_{c} on the xaxis)
2.
Describe the relationship for each graph.
Calculate the slopes for each.
What do the slopes of each graph represent? (Hint: look at
the units for Δy/Δx, then examine your data.)
3.
Describe how adjustments in the radius r would affect the mass=s
velocity given the same F_{c}.
radius
0.85 m;
C
= 2 π r,
T
= time/revs,
v
=
2πr / T
Let g = 10 m/s^{2}
mass
kg 
F_{c}
(N) 
revs 
time
(s) 
T
(s) 
v
(m/s) 
v^{2}
(m^{2}/s^{2)} 
a_{c}
(m/s^{2)} 
0.050 


7.2 
0.72s 



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