2. Methods

2.1       Equipment
- 1 x Pool table, length 122 cm x width 61 cm x height 24.5 cm
- 1 x Cue stick, length 107 cm
- 1 x Cue ball, diameter 4 cm
- 1 x Coloured ball, diameter 4 cm
- 1 x Compact digital camera (Has flat body, no overly protruding parts like flashes, can record at least 720p videos, has a focal length of at most 25 mm and is lightweight). Example “Fujifilm Finepix JX200”
- 2 x Sheets of A3 size corrugated board
- 8 x Aluminum profiles, length 76 cm, base 2 cm by 2 cm
- 1 x Aluminium profile, length 134 cm, base 2 cm by 2 cm
- 12 x 90 degrees triangular connector Gussets, 2 cm x 2 cm
- 24 x Fasteners, size M4 x 8
- 1 x Allen key, screw size no. 6, socket size 0.278 cm
- 1 x Masking tape
- 1 x One meter ruler
- 1 x Pencil
- 1 x Eraser (optional)
- 1 x Blue tack (optional)
- 1 x Geometry compass
- 1 x Scissors
- 1 x Super glue
- 4 x A4 Rough paper

2.2       Diagram

Fig.1 Aluminium Profile Setup

Fig.2 Table Setup

2.3       Procedures

Camera holder:
  1. Measure the length of the camera (Measurement 1).
  2. Measure the width of the camera (Measurement 2).
  3. Measure the diameter of your lens (Measurement 3).
  4. Measure the distances between the lens and the 2 lengths of the camera (Measurement 4).
  5. Measure the distances between the lens and the 2 widths of the camera
  6. (Measurement 5).
  7. Measure the height/thickness of the camera (Measurement 6).
  8. Referring to Measurements 1 and 2, draw them on the corrugated board using a pencil, adding an extra 2 cm for each of them.
  9. Referring to Measurements of 3, 4 and 5, and minusing the added 2 cm to the measurements 1 and 2,  locate the position of the lens on the rectangle drawn on the corrugated board in the previous step and draw the circle at the position.
  10. Using Measurement 6, multiply it by 2, add the length of the thickness of the aluminium profile and add an extra 2 cm (Measurement 7).
  11. Referring to the 2 widths of the rectangle, continue them by drawing the length of Measurement 7 on both sides of each line.
  12. Connect the ends of the 2 lines that was a product of the previous step on each sides by drawing the length of Measurement 2. (Lines 1)
  13. In each of the two lines of “Lines 1”, mark a point where the distance between it and one of the the lines in “Lines 1” is 2 cm.
  14. Take one bar of the aluminium profile and place one side of the bar at the point. Shift the bar so that the side is parallel to the side of the board.
  15. Shift it from right to left until it i estimated to be in the middle of the 2 sides
  16. Trace out the base of the bar on the corrugated board at that position
  17. Repeat on the other side.
  18. Cut out the outer shape or everything drawn.
  19. Cut out the circle
  20. Cut out the shape of the base of the bar.
  21. Slice the 2 lines in the middle of the rectangle, only slicing half the thickness of the corrugated board. It is okay to slice the back or the front part of the board.
  22. Bend the sliced part until it is 90°
  23. Tape it together on the outside and inside. Do not tape the holes.

Aluminium profile:
  1. Connect three 76 cm aluminium profiles together using 2 connectors and 4 fasteners. Make it so that it is the shape of a rectangle with one side open.
  2. Repeat once
  3. Face the 2 open sides to get to form a rectangle.
  4. Use two 134 cm aluminium profiles to connect the two shapes together. Using 4 connectors and 8 fasteners
  5. Use a 76 cm aluminium profile to connect the two 134cm aluminium profiles. Adjust the profile so that it is underneath the pool table. Using 2 connectors which are to be fastened with 4 fasteners underneath the profile.
  6. Skip step 5 if there is no gap underneath the pool table
  7. Take a 76 cm aluminium profile and slide the camera holder in.
  8. Use the 76 cm aluminium profile with the camera holder to connect the two 134 cm aluminium profile at their tip. Using 2 connectors and 4 fasteners.

Cue bridge:
  1. Draw out a rectangle with the width 13 cm and length 17.5 cm on the corrugated board. The width and length just has to be more than 4 cm.
  2. Using the Geometry compass, draw a circle of diameter 2 cm, inside the rectangle, 1 cm away from the side that you are planning to rest on the table and in the middle of the same side.
  3. Repeat Steps 1 and 2, 4 times. Which means that you have 4 rectangles with a circular hole
  4. Cut the rectangles and circles out
  5. Find a flat surface and cover it up using the A4 paper.
  6. Connect the 4 layers by adding super glue carefully. Do not glue the holes.

Pool table and experiment:
  1. Properly set the pool table at a safe and open space. At least 2 m spacing from the perimeter
  2. Place the ruler such that it is in the middle and perpendicular to that of the head rail.
  3. Measure 12.5 cm away from the head rail and mark the point using a strip of masking tape.
  4. Label the strip of masking tape as “Point 1”
  5. Measure 13.5 cm away from point 1 and mark the new point with a new strip of masking tape
  6. Label the new strip of masking tape as “Point 2”.
  7. Place the white cue ball on Point 1
  8. Place 1 coloured ball on Point 2
  9. Place the cue bridge on the wooden part and not on the fabric part
  10. Adjust it from left to right so that the hole is facing straight at the 2 balls.
  11. Tape it tightly down using masking tape. You can add blue tack underneath for extra support.
  12. Make sure that there are no other objects on the table other than those stated.
  13. Place the aluminium profile at place where you can see clearly, at least half the table. Take pictures using the camera to check.
  14. Slot the cue stick into the hole in the cue bridge.
  15. Place the camera into the holder
  16. Use the cue stick to hit the cue ball in the midpoint so that it hits the mid point of the coloured ball.
  17. Place the camera into the holder and record all the shots.
  18. Keep repeating steps 14 and 15 until you have enough data (Recommended at least 60 times)

Tracker:
  1. Download and open the application called “Tracker” (https://www.cabrillo.edu/~dbrown/tracker/)
  2. Open the video in Tracker
  3. Set the scale using the 1m ruler that was placed on the pool table.
  4. Set the axes
  5. Create a new point of mass
  6. Use the autotracker function to track the motion of the ball which marks the position of the ball in every frame
  7. Once the data of the motion of the ball is gathered, define the results that you want to gather.
  8. Define “Displacement = x”   
  9. Define “Velocity = Displacement/t”
  10. Define “Acceleration = Displacement/t”
  11. Results will then be gathered on these definitions based on the video
  12. Read the tables and take down results in a spreadsheet.


2.4       Risk Assessment and Management
  • As this experiment involves pushing solid heavy objects, avoid getting hit by them or breaking them.
  • When placing the camera, you would need to be careful as you might need to stand on a chair to get a better view so there is a risk of falling down. Make sure you holds on to something or someone holds on to you


2.5       Data Analysis
We gathered our data by recording the motion of the balls using a camera. We had many tries, all taken in two videos, with a flat, two dimensional view of the table.
After that, we use a program called Tracker. We set the axes to measure the displacement from the origin and the scale by comparing with the 1 metre rule on the table.

Then, we define the data that is to be gathered from the experiment.

Displacement = x (using the x axis that was set)
Velocity = Displacement/t
Acceleration = Velocity/t (which was then useless as it was inaccurate)

Next, by using the auto-tracking system of the software, we gathered the data and then listed them out on a spreadsheet.

Through the spreadsheet, we found the average Velocity of black ball/Velocity of cue ball of all the data gathered.

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