on due to gravity, g. To do this, we will use a freefall apparatus consisting of a metal object allowed to freely fall b
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on due to gravity, g. To do this, we will use a freefall apparatus consisting of a metal object allowed to freely fall b
Displacement (mm) Ayi= Ay₂= Ay Ay4= Ays= Ay6 Ay₁= Ays= Ay⁹= ΔΥιο= Ayı Ay12= Ay13 Ay14 Time (s) At₁= (1/60) s At₂=(2/60) s At₁= (3/60) s At4=(4/60) s Ats (5/60) s At (6/60) s At (7/60) s Ats=(8/60) s At,= (9/60) s At10 (10/60) s At₁ (11/60) s At₁2 (12/60) s Average Velocity Half Time Intervals (mm/s) (s) ½ At₁=(1/120) s ½/At₂=(2/120) s ½ Ats(3/120) s ½ At-(4/120) s 1/2 Ats= (5/120) s ½/2 At-(6/120) s ½/2 Aty (7/120) s ½ Ats- (8/120) s ', Ato= (9/120) s ½ Atio (10/120) s ½ At₁1 (11/120) s Vavel Vave2 Vave3= Vave4 Vaves Vave6 Vave7 Vave8 Vave9 Vave10 Vavell Vavel2 At₁3 (13/60) s Vavel3 At₁4 (14/60) s Vavel4 ½ At12 ½ At13 At14 (12/120) s (13/120) s (14/120) s 3. The time intervals 1/60 s, 2/60 s,... are already in the table. Each At is the time interval during which the object moved relative to the 1" mark. Now make a careful plot of the object's displacement (Ay) vs. time (At). This plot should fill the vast majority of the graph paper as discussed in class. You can print the blank graph paper from the "Graph Paper" link in Canvas. We expect the plot to be parabolic as displacement varies as time squared for an object subject to a constant acceleration. (See the 1st example graph on the last page.) Put this title on the plot: "Relative Displacement vs. Time". Label the x-axis "Time Interval (1/60 s)" below the axis. Label the y-axis values and write "Downward Displacement" next to the axis. Do not connect the dots or draw in a curve...just leave the points and visually verify that they trace out a parabola. 4. Use the displacements and the time intervals to compute the average velocity of the object during that time intervals. Vavel = Ayı/At1, Vave2 = Ay2/At2, and so on. Can you see a pattern? The increase should be fairly linear.
5. The ½ time intervals in the last column of the table are already written in for you. On another sheet of graph paper, make a plot of the average velocities (y-axis) versus ½ the time intervals (x-axis). *Recall that for a constant acceleration, the average velocity is equal to the instantaneous velocity at ½ the time interval over which the average was calculated...this was shown in lecture and noted it would come in handy. Again, ALWAYS, Use the majority of the graph paper! (See the 2nd example graph on the last page). Label the graph "Average Velocities vs. ½ Time Intervals". Label the y-axis "Average Velocity (mm/s)" and the x-axis "1/2 Time Interval (1/120 s)" 6. Using a straightedge, draw a best-fit straight line through the data points. You will eyeball this as discussed in class. Since the object was already moving at point yo, this line will not go through the origin. 7. Determine the slope of this line by using two points on the curve fit line (not necessarily data points) that are at convenient grid-line intersections as discussed in class. On the graph, circle the two points you used to compute the slope. Do not just count squares! Note that each square has a particular value in mm/s and seconds...don't forget about the 1/120! *The slope of this line is then noted to be the experimentally measured constant acceleration due to gravity since the slope is M = rise/run= Av/At = aave = gmeasured. We know it is downward, so this is just the magnitude. The slope of your line in mm/s² = Compute the %-error between this measured value of g and the accepted value of 9.80m/s² = 9800 mm/s². % Error: % Error = Measured-Actual Actual x 100%