Circular Motion
Objectives: Determine relationship between linear velocity, centripetal force and acceleration.
Equipment: stopwatch, Fc setup, mass set

Methods:
1.  Sketch the Fc setup.  Label the radius, Fc, 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 Fc set up.  This mass represents a force Fc = mv2/r.  Let g = 10m/s2 such that a 50.0 g mass has a weight Fc 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  ac.  The radius remains constant in this lab.

v = 2πr/T  and  ac = v2/r.
5.  Repeat for various masses to get 4-5 trials (up to a maximum of 250 g).

Analysis:
1.  Plot graphs of:

(a)  Fc  vs  ac (ac on the x-axis)

(b)  v2 vs ac   (ac on the x-axis)

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 Fc.

Sample Data Table

radius    0.85 m;   C  = 2 π r,     T  = time/revs,    v  =  2πr / T       Let g = 10 m/s2

 mass kg Fc (N) revs time (s) T (s) v  (m/s) v2 (m2/s2) ac  (m/s2) 0.050 0.50 10 7.2 0.72s 7.4 55 65

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