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

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).

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)




time (s)


T (s)


 v  (m/s)


v2 (m2/s2)


ac  (m/s2)









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