Stoppping Distance

Title: Stopping Distance
Aim: To investigate 1. The effect different surfaces have on the stopping distance of a trolley. 2. The effect different masses have on the stopping distance of a trolley.
Hypothesis:
1. The rougher the surface, the shorter the stopping distance. 2. The larger the mass the further the stopping distance.
Introduction:
The purpose of this research was to investigate how different surfaces as well as different mass effect the stopping distance of a physics trolley after rolled down a ramp. The aim is to test the hypothesis that the rougher the surface, the shorter the stopping distance and the larger the mass the further the stopping distance. Friction is the force which opposes the motion of one surface over another, and is the means through which a vehicle may move in a straight line, or may turn or stop. Stopping distances are affected by friction, the more friction the shorter the stopping distance, the lower the friction the further the stopping distance.
A mass of an object is the fundamental measure of the amount of matter in the object. Weight is the force of the gravity on the object whereas mass is the weight of the object without gravitational pull. Momentum is mass in motion, momentum refers to the quantity of motion an object has. How much momentum an object has depends on two variables, the mass and the speed. Speed is the distance a moving object covers in a certain time. An object that covers long distance in a short period of time has a high speed whereas another object that covers the same distance in a longer period of time has a lower speed. In terms of an equation, momentum is equal to mass multiplied by its speed, therefore an object with a large mass or speed has high momentum. An object with high momentum is a lot harder to stop compared to an object with a lower momentum. This is because with more momentum, more force is applied towards the direction of which the object is moving, therefore the object is pushing harder against the force of the friction hence the friction between the two surfaces is not as effective.

Materials and Methods: 1. Surface A two metre long ramp was inclined 11.5cm above the grass surface. A physics trolley was let go from the top of the ramp, than the distance from the bottom of the ramp to where the physics trolley had stopped was measured with a measuring tape. This method was repeated five times, nothing was altered or moved and the same ramp and physics trolley was used, as well as the person who had let go of the trolley, from the top of the ramp in the first experiment. The method was repeated 5 times and the data was recorded in order to find an average, to get the most accurate result possible. This identical method was repeated on three other different surfaces, concrete, lino and pavers, all five times each, making sure that no other variables were altered. 2. Mass
Surfaces
Surfaces
The above method was repeated once again with the different surfaces. But this time 100g weight was taped onto the physics trolley and let go from the top of the ramp. The distance was collected from the bottom of the ramp to where the trolley had stopped. This exact method was repeated again five times, than the measurements from the experiments were averaged. Next the same procedure was again repeated with the different surface areas but with a weight of 200g. Measurements were collected and averaged. Than the weights increased to 300g than at last 400g, all at while it was made sure that no other variables were altered but surface and mass.
Results
Experiment 1. Stopping Distance Variable 1- Surface | Surface | 1 | 2 | 3 | 4 | 5 | Average | Grass | 88 | 82 | 88 | 91 | 83 | 86.4cm | Concrete | 236 | 280 | 243 | 278 | 288 | 265.0cm | Lino | 270 | 291 | 287 | 294 | 292 | 286.8cm | Pavers | 197 | 188 | 187 | 170 | 182 | 184.8cm |

Experiment 2. Stopping Distance Variable 2- Weight-100g | Surface | 1 | 2 | 3 | 4 | 5 | Average | Grass | 94 | 83 | 86 | 76 | 83 | 84.4cm | Concrete | 310 | 255 | 330 | 252 | 325 | 294.4cm | Lino | 301 | 317 | 331 | 316 | 286 | 310.2cm | Paver | 197 | 202 | 196 | 206 | 197 | 199.6cm | Weight -200g | Surface | 1 | 2 | 3 | 4 | 5 | Average | Grass | 91 | 94 | 89 | 94 | 95 | 92.6cm | Concrete | 327 | 325 | 342 | 290 | 304 | 317.6cm | Lino | 332 | 353 | 361 | 358 | 356 | 352.0cm | Paver | 192 | 187 | 197 | 197 | 197 | 194.0cm | Weight -200g | Surface | 1 | 2 | 3 | 4 | 5 | Average | Grass | 92 | 90 | 95 | 94 | 91 | 92.4cm | Concrete | 286 | 280 | 360 | 380 | 314 | 324cm | Lino | 385 | 372 | 385 | 363 | 416 | 384.2cm | Paver | 183 | 220 | 200 | 196 | 220 | 203.8cm | Weight -300g | Surface | 1 | 2 | 3 | 4 | 5 | Average | Grass | 100 | 96 | 97 | 93 | 90 | 95.2cm | Concrete | 310 | 325 | 371 | 381 | 336 | 344.6cm | Lino | 371 | 359 | 424 | 378 | 404 | 387.2cm | Paver | 206 | 197 | 213 | 85 | 204 | 181.0cm |

Stopping Distances | Surface and Mass | | 0.00g | 100g | 200g | 300g | 400g | Average | Grass | 86.4 | 84.4 | 92.6 | 92.4 | 95.2 | 90.2cm | Concrete | 265 | 294.4 | 317.6 | 324 | 344.6 | 309.12cm | Lino | 286.8 | 310.2 | 352 | 384.2 | 387.2 | 344.08cm | Pavers | 184.8 | 199.6 | 194 | 203.8 | 181 | 192.64cm | Average | 205.75cm | 222.15cm | 239.05cm | 251.1cm | 252.0cm | |

Secondary Source:
Secondary Data: MASS | 1 | 2 | 3 | 4 | 5 | Average | 0kg | 5.10m | 4.65m | 5.15m | 5.05m | 5.25m | 5.04m | 0.5kg | 5.9m | 6.9m | 6.3m | 6.45m | 6.35m | 6.4m | 1kg | 6.8m | 6.1m | 6.7m | 6.7m | 6.55m | 6.57m | 1.5kg | 6.8m | 7.15m | 7.55m | 6.5m | 6.3m | 6.86m |

SURFACE | 1 | 2 | 3 | 4 | 5 | Average | Lino | 4.8m | 5.5m | 6.1m | 3.6m | 3.65m | 4.73m | Grass | 15cm | 17cm | 20cm | 22cm | 16cm | 18cm | Concrete | 4.8m | 4.5m | 4.4m | 4.56m | 4.62m | 4.58m | Road | 1m | 1.12m | 1.34m | 1.64m | 1.4m | 1.3m | Tennis Court | 3.7m | 3.3m | 3.55m | 3.6m | 3.1m | 3.45m |

Discussion:
The first experiment conducted was the stopping distance on different surfaces. The surface with the shortest stopping distance was the grass with an average of 175.7cm, the trolley travelled the second shortest distance on the pavers with an average of 184.8cm which is 9.1cm difference. The concrete had the second longest distance with an average of 275.9cm and the furthest distance which the physics trolley travelled was on the lino having an average of 286.8cm which is 111.1cm more than the results from grass. From these results it seems that the smoother the surface the further the stopping distance.
These results obtained from the experiments can be explained by friction. The different surfaces had different amounts of friction; the friction depended on the texture of the surfaces. The direction of the frictional force of the different surfaces against the trolley is opposite to the motion that the trolley would experience in the absence of the friction. The force of friction is always applied in a direction that opposes movement of the trolley. Every surface has hills and valleys, they all have irregularities, there is no such thing as a totally smooth surface, although, some surfaces have more bumps and grooves than others. In this case the grass had the most, followed by pavers, then concrete and the smoothest out of all, the lino. When two surfaces touch, each of their hills and valleys rubbed against those of the other and cause friction. The rougher the surface, the more friction the two surfaces create, as a result the speed of the surface in motion would decrease quicker than on a surface with less friction until it finally comes to a complete stop. Therefore the grass had the shortest distance because it had more irregularities, thus more friction when it came in contact with the motion of the trolley, followed by the pavers, than the concrete and lastly lino.
Another variable that helped to obtain the results of the stopping distances on the different surfaces was normal force. Normal force is the force compressing two parallel surfaces together and its direction is perpendicular to the surfaces, in this case the two parallel surfaces are the physics trolley and ramp. In the simple case of a mass resting on a horizontal surface, the only component of the normal force is the force due to gravity. If the two surfaces parallel to each other is on a tilt, such as the trolley and the ramp, then the normal force is less because less of the force is perpendicular to the two surfaces. When the trolley is than let go from the top of the inclined ramp gravity takes over and the trolley accelerates downward due to the unbalanced force until it reaches the horizontal surface, than friction works to slow down and completely stop the trolley. Without the normal force the trolley wouldn’t have ran down the ramp, therefore there would be no stopping distance because there would have been no acting motion to begin with.
The second sets of experiments that were conducted was finding out the effect different masses had on the stopping distance. Through the data that was collected as well as the graph it is clear that the trials with the higher mass had further distance compared to those with lighter mass. The average stopping distance for the trolley without any added on mass was 205.75cm, 100g was 222.15cm, 200g was 239.05cm, 300g was 251.1 and lastly the largest mass of 400g had an average stopping distance of 252cm.
As the results show, the stopping distance for the 400g trolley was signifantly higher than the stopping distance of the 100g trolley or the average stopping distance with no mass added on. This is due to the amount of momentum. Momentum is mass in motion, momentum refers to the quantity of motion an object has. How much momentum an object has depends on two variables, the mass and the speed. When the 400g was added onto the trolley, its mass was a lot higher than those of the 100g, 200g and 300g therefore its momentum was a lot more. Combined with natural force and the unbalanced force of being on an incline the trolley’s speed accelerated as it motions diagonally down the ramp. The increase in acceleration allowed to trolley to push harder through the friction allowing it to continue further before slowing down and coming to a complete stop.
Although there was a significant difference between the 400g stopping distance and the 100g and 200g, the difference between the 300g mass was only 0.9cm. This was because at a certain mass, the trolley, the transfer from the inclined ramp to the horizontal surface becomes harder because the more momentum there is the more friction is created when the trolley’s wheel hit the horizontal surface, therefore not going as far is it potentially could have.
The results of the investigation proved the hypothesis to be correct. The experiment for the different surfaces verified that the rougher the surface, the more friction there were therefore the shorter the stopping distance. The lino had the smoothest surface and created the furthest stopping distance with an average measurement of 286.7cm, followed by concrete, than pavers and the shortest stopping distance, with the roughest surface was the grass measuring 175.7cm. As for mass the heavier the mass the further the stopping distance because more momentum was created, this is evident from the results that were obtained. The 400g trolley travelled the furthest on all four surfaces achieving an average stopping distance of 252m. Only 0.9cm behind was the 300g trials, it was explained that the slight difference was due to the frictional impact after the trolley had landed on the horizontal surface. Then following behind were the 200g and then 100g masses. These results are in corroboration with those of the secondary data, although the experiment that was conducted in order to obtain these results were not exactly the methods used to obtain the primary results of this investigation it is similar enough to further prove that the hypothesis was correct.
During the experiments, there were a few hiccups along the way. Firstly the results are not as accurate as there could have been because after the experiments of the first surface, grass, the wheels on the trolley started to become loose so the trolley began to swerve about 130cm after travelling on the horizontal surface. Therefore the trolley travelled a longer distance than what was measured and recorded. This could have been avoided by using a better trolley but that could not have happened because to make it a fair experiment the same trolley had to be used for every single trial. As mentioned before at a certain mass, the trolley, when travelling from the inclined ramp to the horizontal surface the transfer became harder because there were more momentum therefore more so the trolley didn’t travel as far as it possibly could have. This problem could have been avoided by using a ramp with a curved tip rather than a straight, reducing the frictional impact after when transferring from one surface to the other. The research could have been further investigated by having more controlled variables.
Conclusion:
An experiment was conducted to prove the hypothesis that the rougher the surface, the shorter the stopping distance and the larger the mass the further the stopping distance. It was proven that the hypothesis was correct, the results of the experiments show that the rougher the surface the shorter the distance due to the amount of friction caused between the two surfaces. As for mass, the larger the mass, the greater the momentum, therefore harder to stop and further the stopping distance. In relation to road safety, the more friction the tyre and surface make, the easier it would be to control the direction and stop the vehicle, whereas if the force of friction between a tyre and a surface be reduced by ice, snow, rain, oil, mud, loose gravel, a rough surface, or poor tires, then stopping distances will increase drastically and evasive manoeuvres will become much more difficult, or even impossible. As for mass the heavier the vehicle, the harder it would be to stop it because the greater the mass. Thus it is a lot more dangerous, when trying to stop in an emergency or other cases.