Instructions: Show all your calculations, Show units when appropriate During the
ID: 1775625 • Letter: I
Question
Instructions: Show all your calculations, Show units when appropriate During the previous lab, one group used the circular motion apparatus and found that, for a spinning radius of r - 15 cm, the bob of mass m- 700g completes 100 revolutions in 70 s. Using static method, the team balanced the spinning mass at the same distance r = 15 cm using a hanging mass of mb-0.9 kg. a) What was the speed of the bob during the uniform circular motion? b) Using the formula from part (a), and assuming that the absolute error on distance measurement was -1 mm and the absolute error in time measurement was twice the reaction time -0.4 s, estimate the relative error on speed. Hint: Therelative error (%) = absolute error/measured value * 100%. Use the propagation of error rules to estimate the relative error on speed. Assuming that the absolute error on mass measurements is m = 1 g, estimate the instrumental error on centripetal force. Hint: Use propagation of error formula to estimate the error on centripetal force. c) Compute the actual experimental error between the centripetal force and the hanging weight. Compared to the theoretical error from part (c) and explain the difference d)Explanation / Answer
a)
w = angular speed = number of revolutions /time = 100/70 = (10/7) (2 x 3.14) rad/s = 8.97 rad/s
r= radius = 0.15 m
speed is given as
v = rw = 0.15 x 8.97
v = 1.35 m/s