Figure 2: Table of Equipment
Large Electrical fan, variable speed
Identical coffee mugs
Figure 3: Table of Materials
Liquid measuring cup
3-in-1 Instant Coffee Mix Sachets
Figure 4: Diagram of Experiment setup
Measuring the Wind Speed
1. Turn the fan on at its lowest setting, fan power 1. (The fan speed of the lowest setting is dependant to appearance of the fan; size and length of the blades, power of motor, etc.). 2. Place the anemometer on the surface of the lab desk 1m away from the fan. (Use meters per second (m/s) as the units for wind speed).
3. Measure the wind speed.
4. Repeat step 1 of this section for the fan's middle speed, Speed 2 and highest speed, Speed 3. (The different fan speed is dependant to appearance of the fan; size and length of the blades, power of motor, etc.).
5. Make a data table that contains the fan settings and corresponding wind speeds at 1 m from the fan.
6. Graph the data, with the fan setting on the x-axis and the wind speed on the y-axis.
Measuring how wind affects the cooling rate of a cup of coffee
1. Before starting of experiment, measure wind speed for each fan power to confirm wind speed.
2. Label the three cups "#1", "#2" and “Control” using the masking tape and marker. Cup #1 and Control will be used in the experiment. Cup #2 will used as a backup in case of breakage of any of the two other cups.
3. Boil a litre of water in a water heater and dispense 200ml of water into each of the cups with a tablespoon of instant coffee mix. The water should at least be 90ºC. (Higher the temperature, the faster it cools down, so the water must be boiled higher than the needed temperature, 80ºC) 4. Place a saucer on each of the cups to prevent evaporation of the liquids.
5. Cup #1 must be placed 1m away from the fan, while the Control must be placed away from the fan and any drafts. (Away from any drafts which will change the environment, causing the results to be affected)
6. Wait for the liquids to cool to 80ºC and start the timer.
7. Measure the temperature of the coffee cups, as follows:
a. Stir the coffee to ensure temperature is constant throughout the cup and have a
b. Measure temperature by using the laboratory thermometer and wait 30 seconds for the temperature to finish rising.
c. Use the Infrared thermometer to measure the temperature of the side of the cup to double check if the temperature is constant.
8. Record the temperature of each coffee cup at 2 minute intervals for 30 minutes.
9. Repeat step 7 of this section two more times. This enables the results to be more accurate.
10. Repeat steps 7 of this section with the fan set to medium and high speed.
11. Take the average temperature for all wind speeds.
11. Graph the data.
2.4 Risk Assessment and Management
1) Getting burned/scalded by boiling water, stove, naked flames, steam. (Refer to Safety “1”)
2) Breakage of fragile apparatus eg. Beaker, Coffee Cups, Flasks, may result in injuries. (Refer to Safety “2”)
3) Spillage of liquids onto electrical appliances. (Refer to Safety “3”)
4) Electrocution by loose wires, etc. (Refer to Safety “4”)
5) Tripping by loose wires, may result in injuries. (Refer to Safety “5”)
6) Spillage of liquids onto the floor may result in injuries. (Refer to Safety “6”)
1) The group must not tamper with electrical mains and other fittings in laboratories and the group must inform the teacher-in-charge when doing risky activities that include transportation of hot water, using of hot water tank.
2) The group must be alert at all times, and be careful when using fragile materials.
3) The group must keep electrical wirings away from naked flames and heaters.
4) The group must inform the teacher-in-charge in case of any electrical accidents.
5) The group must inform the teacher-in-charge in case of any major/minor injuries.
6) The group must not play a fool in lab and not run around.
2.5 Data Analysis
1. Make four graphs, one for each wind speed and one for the constant.
a. Calculate the average temperatures for each time point.
b. Label the graphs with the fan setting (low, medium, and high) and the wind speed (in metres per second).
c. Put the time on the x-axis and the average temperature of the coffee in cups 1 and 2 on the y-axis.
Figure 4: Sample table
Figure 5: Sample graph