Determine whether the height from which I drop a paper cake case affects how long it takes the paper cake case to fall to the ground.

The only likely risk to people in this experiment is the fact that the 200cm ruler is quite heavy and if not used in the right way dangerous. The possible risk to the equipment which could jeopardize the experiment is the distortion of the paper cake case. Also if the timer is not working properly this could affect the results.

Key Factors

The key factors in this investigation are: the height from which I release the paper cake case and the paper cake case which I use for the experiment. I must use the same paper cake case to make it a fair test and I must change the height from which I drop the paper cake case to prove my prediction.

Valid Evidence

The possible problems I may face with this investigation is that when I let go of the paper cake case I may not let go of it from the exact measurement I record for example when I record dropping the paper cake case from 80cm I may actually drop it from 81.5cm. Another possible problem is when I let go of the case I may not press the start button on the timer at same time I release the case and may not stop the timer at the exact time the case reaches the floor. Precautions that I will take to ensure that the experiment will be fair, although I can not protect the experiment from human error. I will take all the results myself as, if someone else times the fall they are even less likely to start the timer at the same time as the case is released than if I release the case and start the timer myself. I will keep the same paper cake case throughout and will be careful not to distort the shape as this might have an effect on the air resistance of the case therefore affecting the speed at which the case falls which in turn would affect the time it takes to fall.

Equipment

The equipment I will use to carry out my investigation is:

A 200cm A timer

Ruler

A Paper Cake Case

A 200cm Ruler: Set up against the wall, used to measure the height to drop the paper cake case from.

A Timer: To record the time it takes the paper cake case to fall. I will hold it in my hand and start and stop it myself.

A Paper Cake Case: I will hold in my other hand and release at the same time as I start the timer.

Extent and range of measurements

I have chosen to range my results from 60cm to 200cm as this will give a wide range of results. It gives enough results to prove my prediction right or wrong.

Precise and reliable evidence

My evidence needs to be precise otherwise the investigation results and analysis will be false. If I write up an analysis about a set of results that aren't reliable the investigation will be useless. I have planned my experiment as carefully as I can and I believe that as long as I carry out my plans my results will justify this. The main problem I will face is the time will never be precise as the timer I am using only goes to two decimal places therefore making my results only approximate.

Preliminary work

For my preliminary work I decided to do an experiment to test my prediction. The results the experiment gave me are as follows.

Fallen (cm)

Time (seconds)

80

0.75

60

.39

200

.60

After looking at the results from my preliminary work I believe that my prediction is true, by doubling the height from which I drop the case it will double the time it takes the case to fall to the ground. When I do the experiment and take an average over three results I predict that the time it takes the paper cake case to fall to the ground from 80cm will be nearer 0.70 seconds and the time it takes the paper cake case to reach the ground from 160cm will be approximately 1.40 seconds. From the result of the preliminary work I can also predict that the time it will take the paper cake case to fall to the ground from 100cm will be approximately 0.80 seconds.

Results Table

d/cm

t1/s

t2/s

t3/s

t correct/s

t average/s

80

0.79

0.80

0.79

0.79

90

0.85

0.86

0.79

0.86

0.86

00

0.91

0.92

0.89

0.91

10

.01

.03

0.99

.01

20

.06

.09

.05

.07

30

.12

.15

.15

.14

40

.18

.23

.19

.19

.19

50

.27

.26

.24

.26

60

.40

.34

.34

.36

.35

70

.44

.50

.42

.45

.44

80

.32

.51

.52

.52

.52

90

.35

.58

.56

.56

.57

200

.61

.65

.63

.63

Graph

From looking at my graph and table I can see that my prediction was wrong. The graph does however show that the height from which I drop a paper cake case affects how long it takes the paper cake case to fall to the ground, which was the aim of the investigation. The line of best fit proves this, as it is not a horizontal line, which is what it would be if the height did not affect the length of time it takes a paper cake case to fall to the ground. The reason why my results don't support my prediction is because the higher I drop the paper cake case from the more chance it has to accelerate, therefore falling at a faster speed for example, it takes an average of 0.79 seconds for a paper cake case to fall 80cm it fell at a speed of: 80/0.79 = 101.27 cm per second. However it takes the same paper cake case an average of 1.35 seconds to fall 160cm this is at a speed of: 118.52cm per second. Therefore proving my prediction wrong.

Relevant Comment

The procedure was not good enough for me to draw a conclusion with confidence as the timer did not give an exact value, human error was likely as I had to try and start the timer at exactly the same time as I released the paper cake case and then stop the timer at the precise time it hits the ground.

Accuracy of measurements

Although the graph shows points which are not on the line of best fit the variations are only slight and I wouldn't say there are any anomalies. The variations can be accounted for through human error in the method part of the experiment.

Suitability of the procedure

My procedure was not very suitable as I couldn't get an exact result thus I can't draw any meaningful conclusions from them. The only way to improve the procedure would to do it digitally perhaps by using computers and sensors. The only other sensible way to do it manually would be by taking more results before taking an average, perhaps 30 readings.

Reliability of results

If I carried out the same experiment in the same way I would expect to get similar results but if I carried out the same experiment in a different way I would hope to get more precise results. I am however confident with the reasoning behind the results and know why my prediction was wrong.

Extension of enquiry

One way the same experiment could be carried out to get more accurate results is by using photography. A grid should be set up with in front of the digital camcorder to make it easier when analysing the frames of the images which the camcorder will take and transfer to the computer. Once the images are on the computer they can be analysed frame by frame and using the grid lines the time at which it takes the paper cake case to fall can be worked out efficiently and accurately.

Elizabeth Pope 10T Mr.Scanlan