Experimental Design - Amount of Borax Solution

Experiment testing the amount of borax solution used:

Independent variable: The amount of borax solution used.

Dependent variable: The height of the 1^st rebound of the ball.

Controlled variables:

• Concentration of the borax solution
• Type of glue used
• Amount of glue used
• Type of cornstarch used
• Amount of cornstarch used
• Time given for the mixture to react on its own
• Height from which the ball is dropped
• Effort with which the ball is released (free fall)

Apparatus and Materials

• 4g of Sodium Borate (Borax Powder)
• 180ml of PVA (Polyvinyl Acetate) White Glue (in total)
• 100ml of Warm Water
• 180g of Cornstarch (in total)
• Electronic Balance
• 2 Measuring Cylinders
• 2 Plastic Bowls
• 1 Pair of Chopsticks
• Stopwatch
• Long ruler (1m)
• Motion Sensor
• Data Logger

Methodology

Step 1 – Using the electronic balance, measure 4g of sodium borate.

Step 2 – Measure 100ml of warm water using the measuring cylinder. Pour the water into one of the plastic bowls.

Step 3 – Pour the sodium borate into the bowl containing the water. Stir the mixture using one of the chopsticks until the sodium borate has dissolved completely.

Step 4 – Using the other measuring cylinder, measure 15ml of PVA glue. Pour it into the other small bowl.

Step 5 – Measure 15g of cornstarch using the electronic balance and pour it into the bowl containing the PVA glue.

Step 6 – Using the measuring cylinder that was used to measure the water, measure 2.5ml of the borax solution that was made. Pour it into the bowl containing the cornstarch and PVA glue.

Step 7 – Leave the mixture for 15 seconds, timing this with the stopwatch.

Step 8 – Using the remaining chopstick, stir the mixture evenly until it thickens enough to be able to knead into a ball.

Step 9 – Remove the mixture from the bowl and knead and roll it with your hands to form a ball. Leave the ball to dry.

Step 10 – Measure a height of 1m using the long ruler. Position the ball at this height, with the bottom of the ball at the 1m mark. Place the motion sensor 0.2m above the ball.

Step 11 – Release the ball from a height of 1m, recording the movement of the ball with the motion sensor.

Step 12 – Repeat steps 10 and 11 two more times.

Step 13 – Repeat steps 1-12 using 5ml, 7.5ml, 10ml and 12.5ml of borax solution.