An Investigation Into The Effect Of Speed Of A Vehicle On Its Stopping Distance.

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GCSE Double Science Award Physics Coursework.

An Investigation Into The Effect Of Speed Of A Vehicle On Its Stopping Distance.

By Aal-E-Ahmad Hussain

An Investigation Into The Effect Of Speed Of A Vehicle On Its Stopping Distance.

Plan.

To carry out my study into how speed effects the stopping distance of a vehicle I must first identify the factors that affect the stopping distance. The main factors that will affect the stopping distance of the vehicle are the speed, mass, traction and any friction caused by the vehicle. Speed has relevance because the faster a vehicle is travelling; the longer it takes for it to stop. The mass has significance because the vehicle will be travelling purely on its own accord, along with the help of gravity. The traction is relevant and comes hand in hand with friction caused because the tyres or wheels of the car will be coming in contact with the surface of the ramp and the lino floor. The better grip the tyres have will mean that they create more friction with what they are coming in contact with. Also the friction created on the vehicle chassis and the vehicles front and rear axles will also slow the car.

Acceleration is a numerical description of how the velocity of an object is changing. Imagine sitting in a car that is starting off from a stationary position. You look at the speedometer and watch the needle turn as the car gets faster. To get an idea of how quickly the car is picking up speed, you could say how much speed was gained in a set amount of time (let’s use one second because it s the scientific unit of time). To understand this is to understand acceleration.

Acceleration is the rate of change of velocity with time. You can calculate it using the equation below:

Velocity change

Acceleration X Time taken for change

Velocity is measured in m/s, therefore change in velocity must also be in m/s. putting this together gives us units for acceleration of metre per second per second. This is written m/s/s or m/s2.

Naturally objects can be changing velocity if they are slowing down. This counts as a negative change and so gives a negative value for the acceleration. An object can easily have acceleration in an opposite direction to its velocity. Imagine a car slowing down by applying its brakes. The velocity is still forwards, but the change of velocity is negative because it is getting slower giving a negative acceleration, i.e. backwards.

Before conducting my actual experiment I conducted a preliminary test in the same manner just to see which height I should begin with and what clearance distances to use.

Here I shall study the speed of a vehicle weighing 23.8 grams rolling down differing gradients and recording the distance after which it came to a halt. I shall change the gradient of the wooden plank, which is to act as a slope, by changing the height of its rear end. I shall begin by setting its height at 10 cm while its front sits on the floor. I will increase its rear height by 10 cm in my actual experiment. I shall be recording the distance the vehicle travelled after leaving the slope at varying points on the plank. I shall measure the distance from wherever it stops to the front of the plank. To gain average and accurate results, I shall conduct the experiment thrice on each point of release on each gradient and will then deduce an average to plot on my results graphs.

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To proceed with my experiment I shall elevate the rear end of my wooden plank to 10 cm high, using the clamp stand, while the front end sits on the floor. I shall release the car 30 cm away from the front end of the ramp and after that has been done three times I shall increase this clearance distance by ten until the clearance distance reaches 110 cm. I shall ensure that the vehicle has a clear path to travel once it has left the slope and that the path ahead causes minimal friction to obstruct the vehicle ...

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