In this investigation I will investigate the relationship between force, mass and acceleration. Force is proportional to acceleration because if I push a trolley harder the acceleration is higher.

Acceleration = Change in speed / time

                             (m/s2)      =           (m/s2)        /  (s)

The formula for speed is:

Average speed = Distance / time

                                  (m/s)               =      (m)         (s)

The light gate works by timing the time between when something blocks the light beam to when it is reconnected. So if I used a bit of card like the one shown below then If I measure the length of the card then the speed can be measured. Friction will affect the results of the experiment so I will have to compensate for it so the results are accurate. To make the trolley move it will have to be on a slope and if the slope is too steep the trolley will accelerate faster and if it is too shallow the trolley will accelerate slower. To make the slope just right I will put the stationary trolley on the slope and change the gradient until the trolley only just moves then I have eliminated one source of friction. To decrease friction there will be a pulley for the string. Although this decreases friction or eliminates it there are still other sources such as air resistance but these and these will show up on the results. Here is a diagram of my experiment:

I will take 2 results from each variable of Force because this test is likely to be fairly constant and any anomalies can be seen and taken away very easily. I predict that the results will make a straight line graph and that formula above is correct because if I push a trolley twice as hard it accelerates twice as fast. I will do preliminary experiments to measure the correct slope and to input the correct formula into the computer. This will also make sure the experiment will work properly.

Obtaining evidence

I have not included any anomalies as they were very obvious. When I had an anomaly I repeated the experiment again. These occurred for various reasons such as the trolley didn’t  pass through the gate properly. I also repeated experiments when the procedure was not carried out according to the one outlined in the planning.

Analysis

My table shows a general trend that as the force is increased so is the acceleration. It also shows that if I double the force the acceleration is close to being doubled. It also shows that the predicted mass of the trolley using the formula is above the actual mass. This shows that the trolley should be accelerating faster because the higher the acceleration the lower the predicted mass. A graph of my results is attached and it backs p what I have just said as I think it is a straight line and it would pass through the Y-axis above 0. The results are close to what I predicted

Evaluation

The procedure I used worked and gave good constant results. This is clear when you look at the results and notice how close the results are to the line of best fit. It would be more accurate if I had repeated the test more times. The procedure was suitable however inaccuracies occurred because not only did the trolley accelerate but so did the weight. To improve this experiment I would then have to only have one thing accelerating such as a falling object. There is also friction which could be lowered by using thinner wheels and a more streamline trolley. A falling object would also get rid of friction between the slope and the trolley and air resistance could be calculated out of the experiment. The evidence is constant and is so sufficient enough to support the conclusion. It would be more accurate if I had repeated the test more times. Additional data could be collected to further my investigation by changing the weight of the trolley or changing the force.