Finally the fourth experiment compared angles of which the ball bearing descended through a liquid. The results showed a greater angle to the vertical reduced the speed of decent through the liquid.
Initial apparatus
The following apparatus was used to complete the investigation:
2.2 metre plastic tube (colourless)
Diameter 0.03 metre
900ml Water
900ml Engine oil
Five ball bearings with diameter and masses as follows:
Class Mass (g) Diameter (mm)
Very small 0.12 2.96
Small 0.88 6.98
Medium 4.07 9.98
Large 8.96 13.98
Very large 16.69 16.9
Clamp and clamp stand.
Tape measure
Stop clock
Tray
Bung
Magnet
Bunsen to heat oil (in a pan).
Note:
Each experiment shall be repeated 3 times and an average calculated to plot a graph.
Method and Results tables
Experiment 1
For the first experiment, I decided to measure the speed of a ball bearing descending through water.
My final decision on how to complete the experiment was to time the ball bearing at equally spaced intervals. At first, the obvious way to do this was to time at every 10cm interval. However this proved very difficult to do without some sought of mechanical or electrical aid to take the measurement. Therefore I settled for 20cm intervals but timed from a 10cm starting point. This worked particularly well and produced the results that follow this explanation.
Now that I had my first set of results, I thought I would introduce a variable of five differently sized ball bearings. This enabled me to investigate the surface area, mass* and how this effected the rate of descent.
The results of experiment 1 are as follows:
Very Small
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.19 0.21 0.20 0.200
10-30. 0.17 0.18 0.20 0.183
20-40 0.18 0.19 0.20 0.190
30-50 0.20 0.18 0.19 0.190
Small
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.24 0.25 0.24 0.243
10-30. 0.20 0.21 0.21 0.206
20-40 0.18 0.18 0.19 0.183
30-50 0.17 0.19 0.18 0.180
40-60 0.18 0.18 0.18 0.18
50-70 0.17 0.18 0.19 0.18
Medium
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.32 0.33 0.32 0.323
10-30. 0.28 0.28 0.29 0.283
20-40 0.23 0.23 0.22 0.227
30-50 0.19 0.21 0.20 0.200
40-60 0.21 0.20 0.20 0.203
50-70 0.20 0.20 0.21 0.203
Large
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.26 0.28 0.28 0.273
10-30. 0.23 0.22 0.20 0.217
20-40 0.20 0.21 0.20 0.203
30-50 0.20 0.19 0.20 0.197
40-60 0.20 0.20 0.20 0.200
50-70 0.20 0.19 0.2 0.197
Very Large
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.33 0.32 0.30 0.317
10-30. 0.28 0.29 0.27 0.280
20-40 0.27 0.26 0.26 0.263
30-50 0.23 0.24 0.25 0.240
40-60 0.22 0.23 0.23 0.227
50-70 0.22 0.22 0.22 0.220
Experiment 1.2
The second part of the first experiment measured the time taken for five differently sized ball bearings to descend through water. The purpose of this part of the experiment was to make it more clear how surface area and mass* affects the rate of descent.
At this point and introduction of a sixth ball was used. This ball was 'almost' the same diameter as the tube it descended through (22mm in diameter) & (29.02g). Using this ball bearing, I could investigate more deeply into 'up thrust' that wasn't so noticeable with the smaller ball bearings.
The results of the experiments are as follows:
Ball bearing Time taken (s) to descend 1 metre through water
1 2 3 Average
Very small 1.92 1.96 1.94 1.940
Small 1.39 1.42 1.38 1.397
Medium 0.29 1.28 1.28 0.950
Large 1.27 1.30 1.29 1.287
Very large 1.64 1.62 1.63 1.630
Extra large 3.60 3.55 3.59 3.580
On investigation this experiment was not valid as it changed the parameters of the original investigation i.e. the liquid was forced under pressure between the ball bearing and tube.
Experiment 2
The second experiment had all the variables the same apart from the viscosity of the liquid that was changed. The liquid used for this experiment was engine oil.
Although it is easier to measure the rate of descent through engine oil because it is slower, the measured interval remained at 20cm.
The results are as follows:
Very small
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 1.89 1.86 1.88 1.877
10-30. 1.83 1.77 1.80 1.800
20-40 1.76 1.75 1.78 1.763
30-50 1.76 1.79 1.77 1.773
40-60 1.77 1.78 1.77 1.773
Small
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.86 0.84 0.85 0.850
10-30. 0.69 0.67 0.68 0.680
20-40 0.62 0.62 0.62 0.620
30-50 0.62 0.60 0.61 0.610
40-60 0.61 0.62 0.61 0.613
Medium
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.45 0.49 0.46 0.467
10-30. 0.38 0.37 0.39 0.380
20-40 0.39 0.36 0.38 0.377
30-50 0.39 0.38 0.36 0.377
40-60 0.37 0.38 0.37 0.373
Large
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 0.92 0.90 0.91 0.910
10-30. 0.77 0.77 0.76 0.767
20-40 0.48 0.49 0.49 0.487
30-50 0.48 0.46 0.46 0.467
40-60 0.49 0.48 0.47 0.480
Very large
Distance Timed (cm) Time taken(s) for ball bearing to pass through distance measured
1 2 3 Average
0-20 1.52 1.52 1.53 1.523
10-30. 0.68 0.69 0.67 0.680
20-40 0.71 0.71 0.70 0.707
30-50 0.72 0.70 0.71 0.710
40-60 0.71 0.70 0.69 0.700
Experiment 2.2
The second part of experiment 2 investigates the time taken for five various sized ball bearings to descend through engine oil. This allows me to investigate the affect of viscosity on the surface area of a ball bearing.
The results are as follows.
Ball bearing Time taken (s) to descend 1 metre through engine oil
1 2 3 Average
Very small 13.50 13.58 13.54 13.540
Small 5.02 5.05 5.02 5.030
Medium 3.38 3.39 3.37 3.380
Large 3.58 3.60 3.57 3.583
Very large 5.48 5.49 5.48 5.483
Experiment 3
Experiment 3 varied the temperature of the liquid that a ball bearing descended through. I used engine oil for this experiment, as this would prove to have the most change in viscosity when heated. The medium sized ball bearing was used to complete this experiment however all other variables remained the same.
The results are shown below:
Temperature Time taken (s) to descend 1 metre through engine oil
1 2 3 Average
35 2.67 2.65 2.63 2.650
40 2.27 2.29 2.30 2.287
45 2.20 2.21 2.19 2.200
50 2.13 2.17 2.15 2.150
55 1.90 1.91 1.92 1.910
60 1.88 1.72 1.81 1.803
Experiment 4
The fourth and final experiment was to measure the rate of descent of a ball bearing through a liquid at varied angles to the horizontal. I decided to take measurements at every 10o to the vertical.
This experiment would then allow me to investigate and observe if there is any change to the rate of descent caused by the applied angle. I only required taking measurements up to 80o as at 90o the ball bearing would not descend.
The results are shown below.
Angle Time taken (s) to descend 1 metre through engine oil
1 2 3 Average
10 1.69 1.82 1.66 1.723
20 1.87 1.94 1.90 1.903
30 2.20 2.15 2.17 2.173
40 2.46 2.37 2.39 2.407
50 2.76 2.71 2.72 2.730
60 2.92 2.96 2.90 2.927
70 3.54 3.50 3.52 3.520
80 6.15 6.10 6.30 6.183
The next section that starts on the following page displays graphically the results and other relevant information of the experiments mentioned in this report.
Conclusion
A number of conclusions can be drawn from my investigative work into the rate of descent of a ball bearing through a liquid and the factors that affect this.
1) I have found that one of the major factors effecting the ball bearings descent is the size of the ball bearing. From the discussion I mentioned the way in which the liquid flows around the ball bearing as it descends. This proved along with my experiments that the larger the ball bearing the slower the rate of descent. This occured in both engine oil and water.
2) The second major factor was the viscosity of the liquid in which the ball bearing descends. The more viscous liquid made the ball bearing descend at a slower rate.
I can also conclude that the temperature of the liquid in which the ball bearing descends through can increase or decrease the rate of descent. With a higher temperature the liquid becomes less viscous and the ball bearing descends at a faster rate.
3) I have found that the angle in which the ball bearing descends through will decrease the speed of when it will reach the bottom. However as I mentioned in the discussion an extra force was acting upon this and therefore made this experiment invalid.
4) The final conclusion to be drawn from my investigation, is that the ball bearings seemed to reach their terminal velocity in the same timed interval. For experiment 1 it was 40-60 cm and for experiment 2 this was also 40-60. Therefore I would be able to conclude with a third liquid that it may be possible that the liquid does not effect the point in which a ball bearing reaches its terminal velocity.
However I can conclude that the size of the ball bearing and also the mass does not effect where it reaches its terminal velocity. As you already know, if two objects of the same size but with different masses are dropped from the same height they will descend and hit the ground at the same time. It is only air resistance that will affect the descent if the objects size is slightly different. I can relate this to my experiments in finding the terminal velocity of the ball bearings through the liquid, and therefore explain why the occurance happened with only a slight varience with the very large ball bearings.
