# My aim is to plan and conduct and experiment that will allow me to investigate which factors affect the stopping distance of a car

I predict that the speed of the car increases the stopping distance will increase too. This is because the increase in distance means the car will travel at faster speed, however will take slightly longer to reach the end of the slope than the shorter distances. When a car travels, it uses friction to help it stop moving. Because the car is traveling fast and will take a long time for friction to stop the car. Therefore the stopping distance will increase.

Plan:

Method:

* Firstly I will get a pile of books, which has the height of 30cm.

* Secondly I will get two slopes of the same height, width and thickness

* I will then lay one slope off the pile of books and one slope horizontally

* Then I will get the stopwatch, car and ruler ready

* I will measure all the different measurements and mark the points

* Then I will start of with 30cm, as soon as the car is released we would start the stopwatch

* As soon as the car passes through the 1st slope we would make a note of the time and let the car go on until it stopped

* Then we would measure the distance from the start of the 2nd slope till where the car stopped

* We would repeat the experiment 3times for each measurement

* We did the same experiment over again but with different measurements.

Equipment:

* Two flat boards

* One toy car

* Books with the total height of 30cm

* Long ruler to measure stopping distance

* Stop watch to measure how long it takes for the car to travel until it stops

Fair test:

I will look at all the factors that could affect the stopping distance of a toy car

* Gravity. I will not use gravity as a variable in my experiment; this is because it cannot be measured or varied. If you could decrease the gravity on the toy car it would affect the friction between the car and the surface and would decrease the stopping distance of the car.

* The height of the slope because if the slope has a shorter height then the car will travel slowly as it had less gravity pulling on it and there is not much kinetic energy and friction. If the height is greater more gravitational and kinetic energy and more friction between the cars wheel and surface.

* The distance of the car on the slope is varied. When the toy car is released from the greater distance it will take longer for it to role down the slope and will have a greater stopping distance, as there are still lots of kinetic energy and friction left.

* Using the same car on the same surface is important otherwise it wont be a reliable result.

Accuracy:

To get the most reliable and accurate results we will do each separate measurement three times to get the most accurate answer. Then we will find the average.

Safety:

* Make sure not to hit anyone with the board whilst carrying

* Make sure we don’t run our fingers over the car

Computer graph:

This graph shows the stopping distance and final speed

Results table:

Final speed= distance 2 average time

Average= 1st + 2nd + 3rd 3

DISTANCE

(CM)

TIME

STOPPING DISTANCE (CM)

FINAL

SPEED

30CM

1.59

49

40

1.25

46

1.65

48

Average: 1.49

Average: 47.6 (48)

40CM

1.50

59

50

1.69

60

1.62

60

Average: 1.6

Average: 59.6 (60)

50CM

1.59

77

64

1.47

78

1.63

78

Average: 1.56

Average: 77.6 (78)

60CM

2.0

95

65

1.85

92

1.72

90

Average: 1.85

Average: 92.3 (92)

70CM

1.75

99

74

1.65

106

2.25

104

Average: 1.88

Average: 103

Conclusion:

Concluding, looking at the graph we see that the more speed the further the stopping distance. Looking at the graph we see the shape of an “s”, this reinforces my prediction, as it shows that as the speed increases the stopping distance increases.

Evaluation:

When we started the experiment we decided that we would use one person to let the car fall, one person to control the stopwatch and one person to measure. This would make it more accurate.

We also for each different measurement, experimented it three times to make I more reliable and then found out the average. We also made sure that we were following the instructions carefully.

When we first started the experiment we realized that the thickness of both slopes weren’t the same, which meant we had to change one of the slopes to make them the same. Also we later on realized that the height of the books equaled to 25cm when it should have been 30cm so we then increased the number of books to make it more accurate.

Looking at the graph, from “b” to “c” we don’t see a dramatic change in the final speed. We see that the final speed is more or likely the same and the only thing that did change was the stopping distance, which increased. This shows that we might have stopped the stopwatch a bit earlier at “c”.

We could have also as a group is more organized and communicated more.

Overall, I think the experiment did go well, as what I predicted was correct. We have learnt that the higher the speed the higher the stopping distance.