Preliminary Work
Before the actual experiment took place, we decided to do some preliminary work. There was a chance that something could go wrong, for example, the trolley could hit the side of the runway, or the weights could fall off or the ticker timer would not be entirely accurate. So we gave the experiment a test run to make sure everything worked according to plan. The test run went smoothly and so we all agreed the experiment would be a success
Prediction Graph
Equipment
- Runway
- Trolley
- Metre Stick
- Ticker Timer
- Roll of ticker timer tape
- Pulley
- String
- Weights
Diagram
Method
First of all we collected all of the equipment. Then we placed the runway on a raised surface approx. a metre above the floor. Once this had been done, we prepared the ticker timer at the top of the runway. We did this by cutting ticker timer tape to 85 cm (We chose this length because the tape will be out of the ticker timer before the weights hit the floor).
Next, we plugged the wires into the ticker timer in their rightful places and threaded the ticker-timer tape through the ticker timer. Then we placed the trolley at the top of the runway. We then stuck the ticker timer tape to the back of the trolley with tape. Next, we threaded a piece of string through the trolley and attached it to the pulley at the opposite end of the runway. To the end of this string we added different weights according to which experiment we were on. We started with 100g that is equal to 1 Newton in force. Then, on the count of three we simultaneously turned on switched on the mains, which activated the ticker timer and let go of the trolley, which caused it to roll down the runway. It rolled down the runway because the force of gravity acting on the weights pulled it. Once the ticker timer tape was out of the ticker timer we stopped the trolley to prevent it from hitting the pulley at the bottom end. We then switched off the ticker – timer. We then labelled the piece of ticker timer tape to refer to when writing down our results. We then repeated this process for 200g, 300g, 400g, 500g, 600g, 700g, 800g, 900g and 1000g.
Results
Force = 1N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 11.8 ÷ 0.1
=118 cm/s
Time Taken = 12 x 0.1 seconds
= 1.2 seconds
Acceleration = (118 cm/s – 0 cm/s) ÷ 1.2 seconds
= 98.3 cm/s
Force = 2N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 11.1 ÷ 0.1
= 111 cm/s
Time taken = 12 x 0.1 seconds
= 1.2 seconds
Acceleration = (111 cm/s – 0 cm/s) = 1.2 seconds
= 92.5 cm/s
Force = 3N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final Speed = 17.3 ÷ 0.1
= 173 cm/s
Time taken = 8 x 0.1 seconds
= 0.8 seconds
Acceleration = (173 cm/s – 0 cm/s) ÷ 0.8 seconds
= 216.25 cm/s
Force = 5N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 19.5 ÷ 0.1
= 195 cm/s
Time taken = 6 x 0.1 seconds
= 0.6 seconds
Acceleration = (195 cm/s – 0 cm/s) ÷ 0.6 seconds
= 325 cm/s
Force = 6N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 19.9 ÷0.1
= 199 cm/s
Time taken = 5 x 0.1 seconds
= 0.5 seconds
Acceleration = (199 cm/s – 0 cm/s) ÷ 0.5 seconds
= 398 cm/s
Force = 7N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 22 ÷ 0.1
= 220 cm/s
Time taken = 6 x 0.1 seconds
= 0.6 seconds
Acceleration = (220 cm/s – 0 cm/s) ÷ 0.6 seconds
=366 cm/s
Force = 8N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 20.5 ÷ 0.1
= 205 cm/s
Time taken = 5 x 0.1 seconds
= 0.5 seconds
Acceleration = (205 cm/s – 0 cm/s) ÷ 0.5
= 410 cm/s
Force = 9N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 25 ÷ 0.1
= 250 cm/s
Time taken = 5 x 0.1 seconds
= 0.5 seconds
Acceleration = (250 cm/s – 0 cm/s) ÷ 0.5 seconds
= 500 cm/s
Force = 10N
Acceleration = (final speed – start speed) ÷ time taken
Final speed = length of last five-dot strip ÷ time taken
Time Taken = number of five dot strips x 0.1 seconds
Final speed = 24.6 ÷ 0.1
= 246 cm/s
Time taken = 5 x 0.1 seconds
= 0.5 seconds
Acceleration = (246 cm/s – 0 cm/s) ÷ 0.5 seconds
= 492 cm/s
Chart to show results
(Originally I did not include the results to force 4N because I thought it would be interesting to see if I could predict the outcome using my graph. However it has become apparent that my graph is incorrect and this is no longer possible).
Graph
Conclusion
Unfortunately, my graph has not turned out how I expected. The results show me that in my experiment – the acceleration was not directly proportional to the force applied, which (in relation to my scientific research) should not be possible. The graph should be a straight diagonal line (as seen in my predicted graph) however mine was very varied, although it did follow a positive correlation, so we were on the right lines.
Evaluation
My results were not very accurate at all. I feel this is because there were a lot of factors that made it an unfair test despite my efforts to keep it fair. This could also be the reason why there are various anomalous results (it might be possible that all the results are anomalous!) The factors that would have altered my results include:
- Friction. The surface of the ramp caused friction because any type of grip on the surface could slow the trolley down. Also, the surface of the wheels could slow down the trolley because this is the affect of any type of traction provided by wheels. There is little we can do to create a “friction-less” workspace, but to keep it a fair test, we will keep the factors altering friction constant.
- Air-resistance. As the trolley moves through the air the trolley pushes on the air and the air pushes back on the trolley making it speed up less (this is called action and reaction). Again, there is not much we can do about this, but if we were to do this experiment again we would keep the aerodynamics of the trolley constant.
- Slight curve in runway. This makes a slightly bigger force act on the trolley as it goes downhill – therefore it has a greater speed. Next time, we could ensure that the runway is completely flat to prevent unfair alterations to results.
- The ticker timer would alter the result as well. Consider the fact that in every second the tape gets hit fifty times – this must have had some affect on the results. Unfortunately I don’t think we could change this were we to do the experiment again because with the equipment available to us – there is nothing more accurate.
Given more time, I would have liked to repeat each experiment up to five times, to ensure the results were fair –and to prevent the amount of anomalous results. Also, if I were to do it again, I feel that we could extend the experiment. Originally the aim was to find out the factors which affected acceleration. During this experiment we only altered the force and nothing else, it would be worthwhile to alter other things such as the mass of the trolley, the distance, the weight etc. It would be interesting to see if we could prove Newton’s Second Law through other experiments using different trolleys. (His law states that acceleration is directly proportional to the force applied). For example, we have proved (to the best of our ability) that through using the trolley that we did Newton’s Second Law does not work, but would it work for other trolleys?
Abbie Taylor 10KG
