Directions
- Slowly adjust the variable speed control, of the rotator on the apparatus, until the pointer, of the indicator, points towards the index. Keep the speed constant at the critical speed in which the indicator points exactly at the maximum index height. Do not let this speed be exceeded.
- Measure the speed of rotation by starting the revolution counter and timer and allow the rotator to rotate, for about one minute, at a constant speed and then, stop the counter. Note; the timer is synced to the revolution counter.
- Slow the speed down and turn the apparatus off.
- Repeat procedure and take three more readings of the speed.
- Remove the rotator and suspend it from its hanger.
- Tie a piece of string to the metal slug and determine the weight necessary to stretch the spring, so the indicator points to the index. This will be more than you think, so watch out, the string may break. Include the weight of the metal slugs.
- Calculate the force using equation eight.
- While the weight is still on and the indictor points towards the index, measure the radius of rotation, using a Vernier caliper, by measuring the distance from the point of rotation to the center of metal slugs.
- Calculate the centripetal force using equation six. Note; only use the mass that is rotating.
CAUTION: It is dangerous to let the apparatus rotate at excessive speeds.
Circular Motion Results
- Calculate the angular speed of rotation using data collected in the procedures 1 - 4.
- Record the weight needed to stretch the spring measured in procedure six.
- Record the radius of rotation of the mass.
- Calculate the centripetal force using the average speed of rotation and the measured radius.
- Compare the two forces by finding the percent error.
Revolutions
Time (s)
Angular Speed (rad/s)
Trial 1
Trial 2
Trial 3
Trial 4
Average Angular Speed of Rotation_______________________
F = ____________________(N)
r = ____________________(m)
F = ____________________(N)
Percent Error __________________
Rotational Motion Data
Trial 1 - Time 69.80 s- Number of revolutions 603
Trial 2 - Time 59.90 s - Number of revolutions 519
Trial 3 - Time 61.00 s - Number of revolutions 528
Trial 4 - Time 60.85 s - Number of revolutions 527
Mass of the Metal slug on the rotator - 154.2 g
Radius from point of rotation to center of mass of the slug - 5.34 cm
Total mass hanging to stretch the spring - 2450.2 g
Read over Uniform Circular Motion on pp 68-71. Watch the videos on how the lab data is collected then use the data supplied to make all the appropriate calculations and conversions. *NONE OF THE PERCENT ERRORS SHOULD BE OVER 10%* * Please show full work for all problems!!** All the information I was given was included here!*