First we chose a block of wood, it weighed 105g. A Newton metre was attached, which would measures the frictional force exerted on the block when dragged across a surface.
We tried doing the experiment on a smooth surface (table top), but there wasn’t enough friction for an accurate reading. Also when we tried to measure the force with just the block and only a 50 g weight attached the Newton metre did not even give a reading as there was not enough friction on the surface. We then tried carrying out the experiment on a wooden surface (an old drawing board) but again the results weren’t very clear, due to lack of friction. Finally we carried out the experiment on the floor (anti-slip vinyl flooring), the results were much clearer as there was much more friction.
Results for preliminary experiment
Mass of block (g)
Extra mass placed on block (g)
Total Mass (g)
Force exerted on block on the smooth surface (N)
Force exerted on block on the wooden surface (N)
Force exerted on block on the rough surface (N)
I predict that the mass of the block will have an effect on the amount of frictional force. My preliminary experiment results prove this as when we put more weight on the block the frictional force became greater. When the block is pushed down onto the surface of the floor, this causes the two surfaces to lock. A force is needed to push one surface over the other, this causes an equal and opposite reaction. This reaction is friction.
Therefore I think that when the mass of the block is increased the friction will increase as there will be more mass pushing down on the surface of the floor. I predict that the frictional force exerted on the block with different masses on top of the block will be directly proportional. This is because you can see from my preliminary experiment that the frictional force exerted on the block with a weight of 155g (mass of block 105g and additional weight 50g) has a force of 0.2N and then when we doubled the amount of additional weight to 100g, therefore making the total mass of the block 205g, the force doubled to 0.4N. I therefore predict that my results will be directly proportional
We were given a block of wood, which weighed 105g; to the wood we attached a Newton metre, we pulled the Newton metre with the wooden block attached to it across an area of flooring. The Newton metre measured the force of friction and we recorded the results. We then added an additional weight of 50g to the block of wood and repeated the experiment. We did this again but added an 100g, 150g, 200g, 240g and a 300g weights and recorded all these results. I repeated this 3 times.
* Use the same surface throughout the experiment
* Keep the same person pulling the block
* Keep the speed at which you are pulling the block steady
* Use the same person to read the Newton metre each time
* Use the same Newton metre
* Use the same block
Total Mass of block (including extra weight) grams (g)
Force of friction
Force of friction
Force of friction
Average frictional force
I think this graph shows the results very well. I have drawn the line of best fit in with an arrow.
I think my experiment was a success. We can prove this by looking at the graph. The line of best fit passes through nearly all of points, proving that my results are proportional.
In my prediction I said that when the mass of the block is increased the friction will increase as there will be more mass pushing down on the surface of the floor. I predicted that the frictional force exerted on the block with different masses on top of the block will be directly proportional. I think that I have predicted correctly as my results were nearly directly proportional. Also we can see from my results that the friction increased when more mass was added to the block.
We can see from this graph that my results were proportional and that there are not any obvious anomalies. We can see from the arrow I have drawn on the graph that my results are not completely directly proportional. This is because the line does not go through the origin. It is very close though, so I think that my experiment was very accurate. From the line of best fit I have drawn, we can see that there is 1 small anomalie. I have worked out however that it is only 3% away from the line.
I think that my results were more accurate as I repeated the experiment 3 times, and then I averaged my results. This therefore made my results more accurate. We can see that my results are accurate from looking at the graph.