I would also use a tickertape vibrator, as a high degree of accuracy is required in this experiment and any inaccurate readings in my results, I do not want to be due to human error.
The accuracies of these 2 instruments are as follows:
Stopwatch/clock 1/10 s
Tickertape vibrator 1/50 s
The table of results below is to show which method of timing proved to be most accurate:
Prediction:
I predict that the higher the ramp is the faster the speed of the trolley will be and the average velocity and time will not be directly comparative.
Due to gravitational potential energy (GPE), which is the amount of energy that an object has because of its position. The higher the object is the more GPE it has. Therefore at the top of the runway the trolley will have more GPE, than when it has come off the ramp. Therefore at the top of the ramp the GPE is at its maximum and at the bottom of the ramp the kinetic energy (KE) is at its maximum, this is because the energy is being converted, as it cannot be destroyed. Besides I can therefore presume that as the height of the ramp is increased the velocity of the trolley will also increase.
So if Max GPE = Max KE
I can now work out the velocity by using the following formula: velocity = distance/time.
As the height of the ramp is increased there are changes in the GPE and the KE.
However as correct as my predicted results are my actual results will not be exactly like those due to friction. They may be quite similar to the results I got when the ramp is set at a low incline, as the acceleration will be faster meaning less friction will be acting on the trolley. However as the height is raised the trolleys velocity increases and the friction will exert a stronger force on the object and will act as a resistance slowing the trolley down causing some of the energy, which I have predicted to be "lost".
Therefore I predict my results to be slightly lower than the ones predicted, as the height increases the results will even out and won’t be as far spaced apart.
Apparatus:
In the duration of the experiment I will use the following apparatus:
¤ 2 x 1m rulers
¤ A ramp / runway
¤ Clamp
¤ Scales
¤ Trolley
¤ Tickertape Vibrator
¤ Ticker Tape
¤ Power pack
¤ Files and paper
Method:
To perform this experiment, I will work on my own as this will make the experiment less complex. The first thing I will do is set my board at an incline carefully adjusted so that no force will change the speed of my trolley. This will be set-up by clamping the ramp securely at each height I’ll measure so that I can be ensured accurate results. As I discovered in the preliminary that if I set the ramp at a height which was too low it would not travel at a fast enough velocity to enable it to reach the end of the one metre run off, therefore my starting height will be 0.1m. However I also realised that the most elevated height possible would have to be 0.3m otherwise the speed at which the trolley runs off would be too fast and could result in an accident being caused. I decided to use an appropriate range of heights all at the same size interval to prevent confusion when plotting my results and also consequently so that I could be assured a good degree of accuracy in my results. I will then place my file at the end of the ramp, as this will prevent the trolley from "jumping" off the end of the ramp consequently affecting its velocity.
I will then take a power adapter to power my ticker timer dispenser and will connect them using plugs and when the time is right, power it to the correct voltage in order for it to record dots onto the ticker timer paper. I will then cut some self-marking ticker timer paper and thread it into the ticker timer machine assuring that there is carbon paper in the ticker timer device and I will then selo-tape the other end of the tickertape to the back of the trolley. I will then complete setting up my apparatus by hooking the back wheels of the trolley onto the end of the ramp as I have decided that I will measure everything in regard to the trolley in accordance to the rear of it. I will then, be ready.
Diagram to show how I will set up the apparatus:-
Once I have set up my apparatus like so, I will switch the ticker timer on and release the trolley so that it can accelerate down the ramp. I will measure its velocity from the very point it leaves the ramp for one metre. I chose one metre, as it is a suitable distance, if I was to have a number any smaller the trolley may not have yet reached its average speed.
Once I have carried out the investigation, by doing each height 3 times to ensure accuracy I will plot a rough graph. This is so that I can facilely distinguish any irregular results that may need repeating, rather than having to make a guess as to which results are erroneous in a table.
To work out my average speed from my ticker timer paper I will use the following formula:
Average Speed = Distance / Time
Fair Test:
I am very anxious to keep all the factors of the experiment fair and by doing this I will have only one variable element which will be the height as this is what I are investigating. The components which I will keep consistent throughout are:-
¤ Mass of the Trolley; -As the force which will be acting on the ramp must stay the same throughout, and the mass is what will determine this. To control this quandary I will use the same trolley each time.
¤ Friction will slow down the speed at which the trolley travels. A way of reducing the amount of friction is by having a smoother surface and keeping the superficies of the wheels the same.
¤ Air resistance; -I cannot control this to a great extent however I will keep the aerodynamics of the trolley the same each time.
¤ The length of the ramp must remain the same otherwise I will not be able to know whether the acceleration was influenced by the height of the ramp or something else and if the ramp Ire too be extended further this would cause there to be a different velocity.
Safety:
There are no real safety issues to worry about, however to be certain that there are no injuries, I will make sure everyone's ramps are well spaced apart, to prevent any trolleys colliding into anyone and that my ramp is very stable to prevent it collapsing and hurting someone’s foot.
Background Information:
Newton’s law’s of motion:-
- “Every object remains at rest or continues to move in a straight line at a constant speed unless acted on by a force.”
- “When a force does act on an object, the object will accelerate (or decelerate). The value of the acceleration is proportional to the size of the force.”
- “To every action there is an equal or opposite reaction.”
Formulas I might use:-
-
a=∆v/t (acceleration = change in velocity divided by time)
-
F=ma (force = mass multiplied by acceleration)
-
v=d/t (velocity = distance divided by time)
To calculate acceleration "a"
a = Change in velocity (m/s)
time taken (s)
= velocity strip 6 – velocity strip 1 (m/s)
time from 1 to 6 (s)
= (10 x L6) – (10 x L1) (m/s)
0.5 (s)
Bibliography:
Books:
Physics 4 You
Science Exercise Book
Internet:
www.google.co.uk
www.physics4kids.com
www.ask.co.uk
www.clipart.com
www.flamingtext.com
Encyclopaedia:
Microsoft Encarta 98
Microsoft Encarta 2002
© Copyright Prabu Singh England 2003, All rights reserved.