AVERAGE SPEED ON AN AIR TABLE
PURPOSE
To determine the average speed of an air puck, accelerating across an air table due to gravity.
MATERIALS
Air table with timer, 2 air pucks, air pump, mass and string, paper, ruler
PROCEDURE
1.
To avoid a shock, follow the instructions for holding the air puck and not touching the table.
Students with known heart problems should stay away from the table.
2.
Set and record the time interval between sparks at 50 ms.
3.
Make sure one of the air pucks is secured along the edge of the table using the elasticized
holder. (This air puck must remain above the carbon paper for the air table to operate
properly.)
4.
Place a piece of paper on the air table.
5.
Set the other air puck in the centre of the table.
6.
Attach the string connected to the mass, to the air puck in the centre of the table.
7.
Pull the air puck towards you, to the edge of the table, thus raising the mass hanging over the
other end of the table. (Make sure the air puck is on top of the paper).
8.
Make sure you are not touching any part of the table and you are holding on to the rubber tube
on the air puck.
9.
Turn on the air pump and timer.
10.
Press the foot pedal down and hold it to start the spark timer.
(Your teacher will control the foot pedal.)
11.
Release the air puck.
12.
Release the foot pedal when the puck reaches the other side of the table.
(Your teacher will control the foot pedal.)
13.
Turn off the air pump and timer.
(Do not touch any part of the table until this step is done!)
14.
Remove the paper. If the spark trail is not satisfactory, repeat steps 2 to 13 with new paper.
OBSERVATIONS
1.
Create a table to record your data obtained from the air table data sheet. The headings for the
table should include: DOT #, TOTAL TIME (ms), and TOTAL DISTANCE (mm).
ANALYSIS
1.
Examine the dots on your air table data sheet. Choose the first dot that appears on its own (not
touching any of the other dots). This is the “START” dot or dot 0. Label it accordingly.
2.
Measure the total distance from the centre of the “START” dot (dot 0) to the centre of each
subsequent dot. Record the distances in your chart to the nearest mm. (Make sure that you
always measure from the “START” dot).
3.
Record the total elapsed time in your chart for each corresponding measurement.
Remember that the space between each dot represents a time frame of 50 ms.
4.
Draw a total distance (mm) versus total elapsed time (ms) graph using the data that you have
collected. Connect the points on your graph with a smooth curve. Do not use a ruler!
5.
What type of motion does this graph represent?
6.
Using a ruler, draw a straight line from the first point on your graph to the last point. Calculate the slope
of this line (record your answer to 3 significant digits). What does this slope represent?
7.
Draw a diagram of what the dots generated by an air table would look like if the air puck was:
a) moving at a slow constant speed
b) decelerating
Sample Data Sheet
START
d0 d1
d2
d3
d4
d5
.....
dn
Measure all distances from the “START” dot
Answer Sheet
Mark out of 23
Title page: 1 mark; Problem – written out: 1 mark; Mat & Proc – referenced: 1 mark
5 marks for table: 1 mark – correct title; 1 mark – correct headings; 1 mark for correct data points
(MUST INCLUDE – Dot 0, Time = 0 ms, Distance = 0 mm)
Air Puck’s Movement Across an Air Table Due to Gravity
Dot Number
Time (ms)
Distance (mm)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
400.0
450.0
500.0
550.0
600.0
650.0
700.0
750.0
800.0
850.0
900.0
950.0
1000.0
1050.0
1100.0
0
7.0
15.0
25.0
35.0
47.0
61.0
77.0
95.0
114.0
134.0
156.0
180.0
204.0
231.0
256.0
286.0
316.0
349.0
382.0
417.0
453.0
490.0
#5: increasing speed (is a scalar unit – NOT velocity) 2 marks
#6a: Point 1: (ti = 0 ms; di = 0 mm) and Point 2: (tf = 1100.0 ms; df = 490.0 mm)
Vav = (tf – ti) ms / (df – di) mm = (1100.0 – 0) ms / (490.0 – 0) mm = 0.445 mm/ms (asked for
in 3 significant digits)
2 marks: must include units and 3 significant digits
#6b: average speed 2 marks (not velocity – is a scalar unit – NOT VECTOR)
#7a:
. . . . . . . . . .
1 mark: all dots evenly spaced
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#7b:
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1 mark: dots become closer together over time
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. . ..
Distance a Puck Travels on an Air Table Due to Gravity
500.0
450.0
400.0
Distance (mm)
350.0
300.0
250.0
200.0
150.0
100.0
50.0
0.0
0.0
200.0
400.0
600.0
Time (ms)
6 marks for Graph:
1
1
1
2
1
mark for correct title;
mark for correct x axis label and units
mark for correct y axis label and units
marks for data points and best line drawn through points
mark for line drawn from 1st to last point
1 mark for Conclusion
800.0
1000.0
1200.0