Testing The Forces Affecting The Distance A Margarine Tub Travels. Introduction: We are testing for actions or influence that accelerates, or changes the velocity of, an object. An object experiences a force when it is pushed or pulled by another object. For example, shoving a stationary ball applies a force that causes the shopping ball to accelerate. Also a dropped ball accelerates towards the ground because of the presence of the gravitational force; electrical charges attract or repel each other because of the presence of an electric force. Usually, several forces act on an object at once.
If multiple forces combine to give a net force that is zero, then the object will not gain speed or lose speed; the object will either remain motionless or continue moving at a constant speed. Plan: In this experiment I will be testing to see if different forces being added to a margarine tub, affects the distanced the tub is propelled. Possible variables to test; 1) Adding weight to the margarine tub. 2) Changing the tension of the elastic band. 3) Changing the distance the band is pulled back. 4) Adding elastic bands.
5) Change the surface (e.g. concrete) Basic apparatus: Margarine tub Elastic bands Metre rule Weights (100 g-1 kg) 2 x stands Method V 1: In this test I tested to see if adding more elastic band affects the distance that the marg tub travelled. I set the apparatus up shown in the diagram above. I pulled the band's back 10 cm every time. I also added a fixed weight in the tub of 500 g; this helped to give more accurate results.
First I put one band on between the stands and pulled the marg tub back 10 cm and released it, and took down the distance it travelled. Then I added another elastic band and did the same thing. I added 10 elastic band in total, and repeated the whole test over three times. Prediction V 1: If you add more elastic bands to the stand and pull the marg tub back 10 cm every time, the tub will travel further. Because there will be a much larger force being added to the marg tub, this will cause the tub to accelerate and thus travelling a further distance. If you have one band and you add another, the force will be doubled etc.
I predicted that if you add more elastic bands to the stand and pull the marg tub back 10 cm every time, the tub will travel further. If you have one band and you add another, the force will be doubled etc My graph has a straight trend line, this tells me, when the force is increased (adding an elastic band) the distanced travelled by the tub increases. So every time an elastic band is added the force on the marg tub increases to a point where it starts to decrease slightly. Method V 2: In this test I tested to see if adding more weight affects the distance that the marg tub travelled. First I put one band between the stands, added 100 g and pulled the marg tub back 10 cm and release it, and took down the distance it travelled. Then I added another 100 g weight and did the same thing.
I then added 100 g after every result taken down and repeated the whole test over three times. Prediction V 2: If you add more weight to the marg tub and pull it back 10 cm every time, the tub will travel a smaller distance every time you add another weight. Because there will be more friction being created on the marg tub, this will cause the tub to slow down more rapidly and causing it to travel a smaller distance. If you add more weight to the marg tub and pull it back 10 cm every time, the tub will travel a smaller distance every time you add another weight.
My graph has a curved trend line which curves down and then slowly starts to increase, this tells me, when there is more weight added it causes the tub to slow down ant this causes it to travel a less distance. This happens due to the amount of friction being created by the tub and the table. Method V 3: In this test I tested to see if pulling the elastic band back different lengths, affected the distance that the marg tub travelled. First I pulled the band back 1 cm and recorded the result. Then I pulled it back 2 cm and also recorded the distanced it travelled. I did this until I reached 15 cm.
I repeated the whole test over three times. Prediction V 3: I predict that if you pull the band back further each time, the tub will travel a further distance, this is because there is more force being added to the tub. There is a larger force because when the elastic band is stretched it springs back to its original length; only to a point, this is called the elastic limit. If the band passes the elastic limit the molecules in the band change shape and cause the band to change length, and loses it strength and break. So the tub will travel a further distance when the band is pulled back further each time, until it reaches its elastic limit! I predicted that if you pull the band back further each time, the tub will travel a further distance, this is because there is more force being added to the tub.
My graph has a curved trend line which curves up. This tells me that that the more force added (band pulled back) the further distance the object (tub) travels. There is one point at the end of my graph, which drops slightly. This is because the band may have reached its elastic limit. Evaluation: My practical overall was quite accurate, I only had a few anomalies. These could have been caused by releasing the tub, I could have caught it with my finger; also when the tub stops, the weights could have thrown it forward slightly this would have affected the length but not by much.
I could have improved my practical by doing more tests and by securing the weights down in the tub properly. There were a couple inaccuracies in my practical, these were; 1) when I put the weights in the tub I only semi-secured them in. I should have stuck them in securely. 2) when I released the tub I might not have let it go cleanly. If I had more time I could have done another experiment to see if changing the surface which the tub runs on... Prediction ex: I think if you change the surface from a smooth one to a rough surface it would slow the tub down and cause it to travel a less distance because there would be more friction being created.