Module 3 - Section 1 - Motion Experiments and stopping distances Flashcards
How to investigate how - the distance the trolley has rolled - affects its speed ?
First you have to set up the experiment:
1) First get a ramp and lean it against something study so that it doesn’t slip
Then draw a start line on the ramp and then attach a light gate and a data logger to the bottom of the ramp
2) Then you measure the length of the trolley - and make sure that the trolley always starts on the same position by drawing the start point on the ramp
3) Then you measure the angle of the ramp and the distance between the start point and the light gate ( d )
4) place the trolley on the ramp and line it up with the start line and then let it go so that it has an initial velocity of zero - u=0
5) The data logger will then measure the time it takes for the trolley to pass through the light gate and calculate the velocity of the trolley as it passes through the light gate
6) then change the distance by changing the starting point of the trolley ( so that the d is varied )
7) Repeat this experiment for each distance 3 times so that you can get an average result for each result - this is to reduce errors in your final result
You can also use this experiment to measure things such as how does added weight affect speed or change the ramp material to see how friction affects speed
What does a light gate do in experiments ?
it gives a much lower uncertainty in the measurement rather than using a stopwatch and finding the velocity manually
How can you investigate how collisions affect the motion of a trolley ?
Set up:
Get a smooth ramp and put it against a solid object and then at the other end of the ramp put a wall and then get a metre rule for the bottom part of the ramp as the ramp is at an angle then it lies flat on the table - also draw a start line
Then get camera and record the experiment side-on ( perpendicular to the direction of the trolley )
then measure the length of the trolley - then turn on the camera and start recording
Place the trolley on the starting point and let go so that the initial velocity is zero
Once the trolley hit the wall and is at rest - stop recording
Using video analysis software, you can view your videos frame by frame - pick a point of reference on the metre stick and count how many frames it takes a trolley to pass this point
By knowing how many frames per second the video is shot at, you can calculate the time taken (t) for the whole trolley to pass that point. You should have recorded the length of the trolley and so you can calculate its velocity
Time taken for the trolley to pass the point = number of frames for a trolley to pass the point x 1 second/frame rate of camera
Stopping distance =
Thinking distance + breaking distance
Whats reaction time ?
Reaction time is the time your body takes to react and hit the brakes after seeing a hazard
Whats the thinking distance ?
The thinking distance is the distance the vehicle travels during the drivers reaction time
Whats the breaking distance ?
The braking distance is the distance the vehicle travels after the brakes are applied until it comes to a complete stop
What does thinking distance =
Speed x reaction time
What can reaction time be increased by ?
- tiredness
- alcohol or other drug use
- Illness
- Distractions such as noisy children and loud music
What does breaking distance depend on ?
Braking distance depends on the braking force, friction between the tyres and the road, the mass and speed of the car
How is braking force reduced ?
Braking force is reduced by reduced friction between the brakes and the wheels ( worn or badly adjusted brakes )
How is friction between tyres and the road reduced ?
Friction between the tyres and the road is reduced by wet or icy roads, leaves or dirt on the road, worn-out tyre treads, etc
What’s the mass of the car affected by ?
It’s affected by what you put in the car and by the size of the car
