It was found that 5i?? C was too cold for the ball to move at any timeable rate and would have taken hours to reach the 10cm point and so no readings could be taken. It was also decided that anything above 40i?? C would allow the ball to move too quickly through the honey to be timed to a good degree of accuracy.
During the preliminary work I noticed that when the ball with the attached straw was placed in the measuring cylinder of honey the straw did not move vertically downwards, it instead leant against the edge of the measuring cylinder which got increasingly covered in honey as the experiment went on causing drag and slowing the ball bearing down. In order to prevent this I used a small piece of cardboard with a hole in just big enough for the straw and placed it on top of the cylinder, this held the straw upright causing very little drag. Fair Testing
The same ball bearing and straw will be used every time to ensure that it is exactly the same shape and weight for each temperature of honey. The ball bearing will also be washed in hot water after each reading has been taken so the shape of the ball is not altered affecting viscous drag. They will also be cooled to room temperature using tap water and dried so it is the same temperature in for every reading. The honey will be kept out of the sun whilst the experiment is being carried to keep it from warming up affecting the speed at which the ball bearing will travel through the honey.
Range From looking at my preliminary results I can see that the range has reached its limits when the honey is 11i?? C and 40i?? C as after these temperatures it will be very difficult to take accurate readings. I have therefore decided to use temperatures of 10i?? C to 40i?? C going up in 5i?? C intervals. Engineering in Design During the preliminary experiment it was found that we had problems in measuring the distance that the ball bearing had fallen and also struggled retrieving the ball bearing from the honey.
In order to solve this problem I decided to attach a drinking straw to the ball bearing. This was done using araldite, a strong quick drying water resistant adhesive. This meant that the ball bearing could be retrieved easily from the honey after each reading was taken. I marked the straw twice, one marking 5cm from the ball bearing and the other 15cm from the ball bearing, I would start timing the ball bearing after the 1st line is submerged in the honey, leaving 5cm for the ball bearing to reach terminal velocity, the stopwatch would be stopped when the 2nd line gets submerged.
This method ensures that for each reading the ball bearing has the same distance to reach terminal velocity and is being timed over the same distance consistently. 5cm 10cm Attaching a straw to the ball bearing created a new problem; it was found that the straw would lean against the edge of the measuring cylinder in which the honey is.
The edge of the measuring cylinder tended to be very sticky due to having small amounts of honey around it, this caused extra drag slowing the ball bearing down and giving inaccurate readings. This problem could be easily solved however using a small piece of card just big enough to cover and rest on the top of the measuring cylinder. This piece of card would have a small hole in the centre, achieved using a hole punch, that would hold the straw upright so that accurate readings can be taken.