Find out how changing the surface which a margarine tub is launch on, influences how long it takes it stop.

        I will be measuring the distance from the front of the tub when it is pulled back into the elastic band, to the front of the tub, when it stops.

I will keep the Mass, Thrust, and Size of the tub the same. By doing this it will keep the test simpler. Plus make the results more reliable, because there are not so many things to check and things which could go wrong.

Prediction:

        I predict the rougher a surface is the small the stopping distance. I think this will occur because there is a lot of resistance from the rough surface on the base of the tub, causing a lot of friction, which slows an object down quickly. This happens because there are many bumps rubbing against the base of the tub, which hit each and sometimes interlock with each other and so will bring the tub to a stop faster, than if the surface was smooth and didn’t have as many sticking bumps/fibres to hit and inter lock with and slow it down.

(Picture from Encarta 2003)

 

Plan:

To do this experiment I will need to use:

• Stool: ( to be as a base to launch the margarine tub)
• Elastic band: ( Will propel the tub forwards)
• Tape measure: (Measure the distance the tub travels)
• Margarine tub: ( the object which will be propelled over different surfaces)
• Different surfaces: (To see how they have an affect on the stopping distance, the surfaces are: Soft Carpet, Rough Carpet, Lino, Perspex, Polished Wood, Sandpaper and wood.)
• Newton Meter: (to make the tension on the elastic band 10N)

    We will measure the distance it took the tub to stop in Centimetres, and measure from the front of the stool to the back edge of the tub. This will help keep the test fair, as we will not be measuring to different places for each launch.  To make the thrust given to the tub each time, is the same, I will use a Newton meter, and pull the elastic band back 10N.

        

• Set up equipment (as shown below)
• Choose a surface, and record which one you have chosen
• Lay the surface down, and get the tub ready for launch
• Put the tub in the centre of the elastic band, and pull it back till the tub is on the pre-set line, for launching
• When ready release the tub, and leave it until it was come to a complete stop, some wear along the surface.
• Get a measuring device (metre stick/ tape measure) and measure from the front of the stool, to the back of the tub.
• Record the distance next to the surface, and repeat that same test 1 or 2  times more.
• When you have 2 results for that test, then change the surface, and repeat the process.

 

        The experiment isn’t that dangerous, but we will make sure that no one is standing in the firing line of the tub, so not to hit anyone. We will also do the experiment on the floor and not on a desk, so that there’s a lower chance of it hitting some. We will make sure that the elastic band isn’t too stretched so that I wont snapped and flick and hit someone.

         

           

Observation:

        

Analysis:

(Table on back page graph on this page)

        The results show that my prediction was correct. ‘The smoother the surface the larger the stopping distance’ This is easy to see, as the average distance between the smoothest and roughest surface (Soft carpet/Polished wood) is 113cms, which is just over 4times further. The pattern I can is that the rougher the surface the shorter the stopping distance is. The higher the marks are on the graph, the further the distance covered by the tub before it stopped.   

Polished wood travelled the furthest many because the surface is polished so it acts like a lubricant keeps the surface smooth, it covers up any particles fibres which mite enhance the force of friction. It is also like ice, as it freezes it stays level, and produces a smooth sliding surface.  

        Perspex had the 2nd longest distance as it’s a very smooth surface, but it wasn’t that clean so there would of bean some particles/fibres which the base of the tub would have run along slowing it down.

        Sandpaper had the 3rd longest distance which was surprising as there a hundreds of sand particles all over the paper which the base of the tub would have rubbed against. But as the particles were quite lever the tub would have skimmed against the surface, but some of the sand would of slowed it down.

        Lino was 4th, I think it didn’t travel that far as its made out of a plastic/rubber which is a very grippe surface. So would of slowed the tub down a lot as it would of gripped to the bottom the bottom of the tub.

        The carpets were 5th and 6th, which was no surprise as they have a lot of fibres sticking out of them. This would of come into contact with the front and the base of the tub and slowed it down considerably.

Evaluation:

        The test was a success as I got good results, which proved my prediction correct. We had no problems recording the data in my table or inputting it on to a graph. The equipment I used was reliable and all help keep the test fare and make the measurement accurate. The results were accurate, because we repeated the experiment so to make sure the test went right and something hadn’t gone wrong, like the tub taking off as the elastic band launched it, as this would of made the distance much further as the tub would of covered ground without the surface affecting it.

        The only result which I wasn’t to worried about was the sandpaper, as I thought it would have had a shorter stopping distance, but I was reassured after I tested it again, and the distance was about the same. I had enough results to show ‘how changing the surface will affect the stopping distance of a margarine tub ’As I could prove my prediction right. If I repeated the experiment again, I wouldn’t need to change anything, apart from using more surfaces. But it would have been easier to use something else to measure the tension of the elastic band, as unhooking the Newton meter was difficult with out moving the elastic band.