I am going to investigate how the mass of a margarine tub affects the distance it can travel.
The following Factors will affect the distance the tub can travel:
·Surface area of the tub
·Force applied to propel tub
·Length of elastic bands used to propel tub
·Surface on which tub will travel
I predict that as the mass of the tub increases, the distance the tub can travel will decrease. This is because of friction. Friction is the force that resists the relative motion or tendency to such motion of two bodies in contact. Each time the mass of the tub is increased the pressure between the two contact points (the bottom of the tub and the floor) increases and thus the friction force acting in the opposite direction of the forward forcer of the tub overbalances it. This causes the tub to slow down and stop at a shorter distance each time its mass is increased, because the friction force becomes increasingly greater than the forward force of the tub.
I carried out a preliminary work to gain enough evidence to support my prediction and find out what was the best apparatus, range of weights and surface to use in my experiment.
·100 cm ruler
·10 100g weights
I stretched an elastic band between two stool legs (40 cm apart) and pulled it back from the stool legs 30 cm, using a ruler to measure; thus using Elastic Potential Energy as the force to propel the tub along the floor - my chosen surface. I celotaped the weights to the bottom of the tub to prevent them falling out and/or overturning it in motion, placed the tub in line with the stool legs and let go of the elastic bands. The weights I used are 10, 30, 50, 70 and 90g weights. I measured the distance the tub travelled along the floor from the stool legs with a 100cm ruler.
Weight put in tub (g)Distance tub travelled (cm)
My preliminary results show that the greater the mass of the tub the shorter the distance it travels.
·10,20,30,40,50,60,70,80,90 and 100g Weights
To ensure this is a fair and safe test I will:
·Only change 1 variable the mass of the tub. I will use 10-100g weights because this range of lengths should increase the accuracy the results because the more readings taken give statistically more representative results.
·Use a piece of string to pull back the elastic band. I found out from my preliminary results that pulling back the elastic band with my fingers affected the tests because my fingers got caught up and it hurt. The elastic band failed to propel properly until I used the string and repeated the tests. The experiment was much more accurate and reliable. ·
I am going to record my results in a table. I will ensure my results are reliable and accurate by repeating each test of every weight from 10 to 100g three times. If one result is significantly different to both the other 2 results, I will repeat the test a 4th time to replace the anomalous result. I will then work out the average results and plot them on a graph.
My results support my prediction and prove that the mass of the tub increases; the distance the tub can travel decreases. There is
The experiment proved to be a success. I believe that this experiment was suitable for the investigation because I completed the aim that I set out to achieve. I obtained evidence proving that as the mass of the tub increases, the distance the tub can travel decreases.
Most of the results fit on a definite curve on the graph. There are 3 results: 20g, 30g and 90g, which are marginally off the curve but I don't agree that they are anomalous because they are not of significant enough difference.
Although I believe my experiment was accurate and reliable as I repeated every test 3 times and used the average results to plot the graph; and took every care to make sure that it was fair so that no mistakes could be made. - what may have occurred to fault the accuracy and reliability of this experiment:
The distance the tub travelled may not have been precisely accurate. Using a ruler (accuracy to nearest 0.5 cm) this could jeopardise the accuracy and reliability of the results.