PASCO ME-8950A COMPLETE ROTATIONAL SYSTEM - Manual (Page 26)

Complete Rotational System 012-05293F
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5. Calculate the mass of the object from the slope and record in Table 3.4.
6. Calculate the percent difference
between the two values found for
the mass of the object and record
in Table 3.4.
Part III: Vary Mass (constant radius and force)
The centripetal force and the radius of rotation will be held constant for this part of the experiment.
1. Weigh the object with the additional side masses in place. Record its mass in Table 3.5. Hang the
object from the side post and connect the string from the spring to the object. The string must pass
under the pulley on the center post.
2. Attach the clamp-on pulley to the end of the track nearer to the hanging object. Attach a string to
the hanging object and hang a known mass over the clamp-on pulley. Record this mass in Table
3.5. This establishes the constant centripetal force.
3. Select a radius by aligning the line on the side post with any desired position on the measuring
tape. While pressing down on the side post to assure that it is vertical, tighten the thumb screw on
the side post to secure its position. Record this radius in Table 3.5.
4. The object on the side bracket must hang vertically: On the center post, adjust the spring bracket
vertically until the string from which the object hangs on the side post is aligned with the vertical
line on the side post.
5. Align the indicator bracket on the center post with the orange indicator.
6. Remove the mass that is hanging over the pulley and remove the pulley.
7. Rotate the apparatus, increasing the speed until the orange indicator is centered in the indicator
bracket on the center post. This indicates that the string supporting the hanging object is once
again vertical and thus the hanging object is at the desired radius.
8. Maintaining this speed, use a stopwatch to time ten revolutions. Divide the time by ten and record
the period in Table 3.5.
9. Vary the mass of the object by removing the side masses. Keep the radius constant and measure
the new period. Weigh the object again and record the mass and period in Table 3.5.
Table 3.3: Varying the Centripetal Force
Centripetal Force = mg Period (T)
1
T 2
Mass of the object =
Radius =
Slope from graph =
Mass Over Pulley
Mass of Object (from scale)
Mass of Object (from slope)
Percent Difference
Table 3.4: Results (varying the centripetal force)