Ramp's Surface The Speed Of The Trolley example essay topic

Friction Investigation Introduction In this experiment the aim is to discover which material opposes the motion of a trolley travelling down a ramp. This opposing motion is called friction and acts between two surfaces. To determine which material has opposed the motion of the trolley the most, the speed at which the trolley travels down the ramp when a material is used on the surface of the ramp will be measured. In this experiment the independent variable is: The different materials used for the surface of the ramp. The dependant variable of the experiment is: Due to the alteration of the material used on the surface of the ramp, the speed at which the trolley travels down the ramp will differentiate for each material used.

The control variables of the experiment are: The equipment used when the experiment is repeated. The length of the different materials used to cover the surface of the ramp. The height and angle of the ramp when the stool is used as the support. The distance between the two sensors positioned along the ramp.

The distance allowed for the run up to the first sensor. The other factors, which I could investigate that affect the friction of the trolley: The force pressing the surfaces together. The aerodynamics of the trolley. The weight of the trolley. The height of the ramp. The different grades of sand paper available on the market.

Background information Friction is a force that acts between solid surfaces as they move over one another, and when objects move through a liquid or gas. The force of friction is caused by the roughness of two surfaces. If the surfaces are clean and dry, the force needed to overcome friction depends upon: The materials from which the surfaces are made. The surface finish, i.e. rough, smooth or polished. The force pressing the surfaces together. Friction between contacting surfaces is often a disadvantage because it produces heat and wear.

Friction can be reduced by the use of ball bearings and lubrication. Water, snow and ice all reduce the grip between the ground and the object moving over the surface (e.g. a vehicle.) When there is water or ice on a road, the humps and hollows of the rough road surface are levelled out. The reduced friction causes cars and other vehicles to skid, as the tyres are unable to grip the ground. Reduced friction makes it more difficult to stop a car.

The brakes stop the wheels from moving, but if there is not enough grip between the tyres and the road the car will slide forward. When an object is moving there are two main forces at work, acting in opposite directions - the force that is exerted, propelling the object forward, and friction. The friction creates a drag in the opposite direction to movement and so it tends to slow the object down. If there is no friction (as there is in space) then once an object moves it will continue to move forever.

Sources used in order to comprise the background information: GCSE Science Double Award, Physics - K Foulds. Page 120 & 121. Letts, GCSE Revision notes, science higher - Page 75. Schools Council Modular, Courses in Technology, MECHANISMS - Oliver & Boyd. Pages 129 & 132.

The question that I want to answer after conducting this experiment is: Which material slows the trolley down the most? Prediction I predict that if sand paper is used on the ramp's surface then the speed of the trolley will be slower when compared to the other materials used on the surface of the ramp. The reason why I believe that the speed of the trolley will be slower when sand paper is used on the ramp's surface is because of the following reason: Sand paper has a rough surface when clean and dry and thus will prevent the trolley from travelling down the ramp - there will be more grip between the wheels of the trolley and the surface of the ramp and this will therefore slow the trolley down, because the force of friction (acting in the opposite direction to which it is travelling) is greater than the force of exertion that propels the trolley down the ramp. References used in order to comprise this prediction: GCSE Science Double Award, Physics - K Foulds. Page 120 & 121. Pages 129 & 132.

Fair Testing To make this experiment a fair test, the following criterion need to be met: The equipment used will be the same when the experiment is repeated. The length of the different materials used to cover the surface of the ramp will be 75 cm. The height of the ramp when the stool is used as the support, which is 23 cm. The distance between the two sensors positioned along the ramp will be 75 cm. This distance will be 30 cm. Accuracy To make the results gained from this experiment accurate, the following conditions need to be enforced while conducting the experiment: Ensure that the trolley isn't pushed down the ramp.

The trolley should be released down the ramp with its spring facing downwards. The distances and heights will be measured exactly with precision and accuracy with the use of a ruler. If the material being tested isn't long enough to stretch across the distance of the two sensors, ensure that there are no gaps or overlaps between the pieces of material that are used to compensate for the full length. Safety To make this experiment safe the members of my group will do the following procedures: A buffer will be positioned at the end of the ramp in order to prevent the trolley from travelling further along the corridor. All stools and other objects that may obstruct the apparatus of the experiment will be placed elsewhere.

The trolley must include a spring so it can absorb the shock after hitting the buffer. Method Equipment needed in order to carry out the experiment: Stool Ruler Ramp Trolley Data logging equipment - included with a computer School bag (to used as the buffer) 2 x Clamps Tape Black card Sandpaper Wallpaper Lino Cling film Control - the material the ramp in made of (wood). Carpet 1. Get stool and place ramp on the support of the stool (this support is 23 cm in height.) At the bottom of the stool position a school bag. 2. Plug the computer into the socket and open the data-logging programme.

The data logging equipment will be used to measure the speed at which the trolley is travelling down the ramp. 3. Position the two clamps so that they are 75 cm away from each other. Ensure that before the first clamp, there is 30 cm allowed for the 'run up' distance to the first sensor. 4. Plug each of the sensors into the appropriate sockets and clamp the sensors with the use of the clamps.

5. Attach a piece of black card vertically onto the trolley with the use of tape. This black card will be used so that the sensors do sense the trolley as it passes down the ramp. Adjust the height of the clamp so that the trolley does actually pass through the sensors.

6. Secure a piece of sandpaper (with tape) to the ramp so that it stretches across the distance of the two probes (75 cm). If the piece of material isn't obtainable in that length then use the pieces of the same material to compensate for that length. When doing this make certain that there are no gaps between the pieces of material or there are no overlaps are evident. 7. Place the trolley at the top of the ramp before the run up distance to the first sensor and simply release the trolley.

Before releasing the trolley make sure that the data logging system is set to 'ready'. Also check that the trolley's spring is facing downwards when each test is conducted. 8. Before each of the tests are carried out, a test run will be required to see whether the sensors situated along the ramp has sensed the trolley movement down the ramp.

If not then this means that the height of the sensors above the ramp will have to be adjusted so that the trolley does pass through the sensors. 9. Repeat the procedures mentioned in step 7 through to 9 six times for each of the 6 different materials to obtain average results, which will then be plotted on a graph. Repeating the experiment six times for each material being tested will allow reliable results to be processed. 10. To test another material, replace the current material being tested with a different material, reciting steps 7 through to 10.

Diagram: The diagram below shows the equipment once it has been set up. These average results were then included in the bar chart shown below.) Conclusion From the processed results I conclude that when carpet was used on the surface of the ramp, this caused the most friction between the trolley and the surface as the speed of the trolley was a lot lower compared to when the other materials were used on the ramp's surface. Most of the results that I obtained appear to have a relatively large difference when the tests were repeated for each material. For example when the first test was carried out with sand paper the speed of trolley was 0.88 m /'s in the second test that was conducted the result was 0.67 m /'s there is a difference of 0.21 m /'s !

The only set of results that seem to be reliable are the wallpaper results, as the results for each of the tests seem to be around the same number and thus there isn't a large difference. The results (shown in the results table) would therefore substantiate that my prediction was incorrect as I stated that if sand paper was used on the ramp's surface the speed of the trolley would be slower when compared to the other materials used on the surface of the ramp, when in fact it was carpet that produced the most friction out all of the materials due to the speed of the trolley being lower. The reasons why carpet slowed down the speed of the trolley is because: The carpet that was provided for use in this experiment was considerably thicker than the other materials and due to this feature there was more grip between the wheels of the trolley and the surface of the ramp and this therefore slowed the trolley down, because the force of friction (acting in the opposite direct to which it is travelling) was greater than the force of exertion that propelled the trolley down the ramp. If one refers to the bar chart one will discover that the bar showing the average speed of the trolley when carpet was applied to the ramp is lower down than the rest of the bars, indicating that the speed of the trolley was low compared to the speed of the trolley when the other materials were used, this would also prove that the results undermine the my prediction. Evaluation Overall this experiment went well, the members of my group and I encountered no problems while conducting this experiment. Personally I think that the results gained after conducting this experiment are unreliable as I realised that there were a number of anomalies with the results that my group didn't repeat, as there wasn't a sufficient amount of time to achieve this.

The reason why I believe that there are anomalies in the results is because when the tests were repeated for each material there appeared to be a relatively large difference between the results for each of the tests. One example of this is in the results was when the first test was conducted with sandpaper - the speed of the trolley was 0.88 m /'s in the second test the result obtained was 0.67 m /'s - a difference of 0.21 m / 's. The reasons why I think that these anomalies in the results occurred is because... The trolley may have been given a push down the ramp instead of being released down the ramp due to the force of gravity acting upon the trolley. The distances and heights may have been measured inaccurately or may not have been the same when each of the different tests were carried out. There may have been gaps and overlaps between the pieces of material that were used.

The sensors used to detect the trolleys movement may not have been triggered by the trolley when the tests were carried out. There may have been indentions along the ramps surface. Throughout the experiment I think that we were quite accurate to acquire accurate and reliable results because: we ensured that the trolley wasn't pushed down the ramp and allowed the trolley to be released down the ramp with it's spring facing downwards; the distances and heights were measured exactly with precision with the use of the ruler and when the material wasn't long enough to stretch across the distance of the two sensors, we attempted to ensure that there were no gaps or overlaps between the pieces of material that were used to compensate for the full length. Despite abiding to these measures that I proposed to enforce in order to make the experiment as accurate as possible, anomalies in the results did still occur and this may have been because the members' of my group and I didn't enforce the measures for accuracy with skill. I believe that there isn't enough evidence to support a firm conclusion, because we didn't repeat the anomalous results, as there wasn't enough time to do so.

These anomalous results should have been repeated to gain a more reasonable result, and then for sure I will be certain that prediction is either right or wrong. To improve the existing experiment to obtain more reliable and accurate results I would: use materials that weren't available in separate pieces - I would ensure that the material was already cut to size with accuracy; make sure that the trolley isn't pushed down the ramp; make certain that there is enough time to recite any anomalous results; use a ramp that doesn't have any indentions - I will use a ramp with a smooth surface and before conducting each and every test I will firstly make absolutely sure that the sensors do get triggered by the trolley's movement down the ramp. To take the investigation further I would investigate each of the other factors that affect the friction of the trolley travelling down the ramp: The force pressing the surfaces together. The height of the ramp.