# Science Changing A Surface Affects The Essay

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Aim:I am going to find out how changing the surface which a margarine tub is launch on, influences how long it takes it stop.Variables:During this test I have a chance at changing the variables, which are:* Mass, (how much weight I amply to the tub) If I changed the mass in the tub, it would either get heavier or lighter. If the mass increased the pressure on the surface would also increase, which would push the tub against the surface harder so it will slow down more as its more likely to hit fibres/particles.* Surface (how rough or smooth the surface it) If I change the surface to a smoother one, it will slide better and take longer for it to slow down, as there want be as much friction acting on the base of the tub, as there is less fibres/particles sticking up, which would come into contact with the base of the tub.

* Thrust (how much energy I use to propel the tub forward) If I propel the tub faster, then it will take longer for the tub to slow down, as it has to slow down from a higher speed.* Size ( how big the tub is (how large the surface area is, which is in contact with the running surface) If I increase the surface area of the tub, then there will not be more friction, but just a larger area on which friction will act, and so will slow the tub down.I will only change the surface in which the margarine tub will be running on. The surfaces I will use will all be different from very rough to very smooth.

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.