∙ Gravity will stay constant by keeping the experiment at the same level and same place.
Changed
∙ The height of the ramp will increase every 10 cm up to 60 cm. This is to spread the results out and make it easier to see patterns.
Equations:
∙ speed (metres/ second) = distance (metres)
time (seconds)
∙ velocity (metres/ second) = distance (metres)
time (seconds)
∙ kinetic energy (joules) = velocity2 ( metres /second2) x mass x ½
∙ potential energy (joules) = weight (grams) x gravity (newtons) x height (cm)
Method:
∙ Set up the apparatus as shown in the diagram.
∙ Make sure the ramp is 10 centimetres high.
∙ Place the car at the top of the ramp and set the timer to zero.
∙ Release the car and press ‘go’ on the timer simultaneously.
∙ Let the car come to a halt and press stop on the timer at the same time.
∙ Record the time taken.
∙ Raise the ramp a further 10 centimetres.
∙ Repeat the test twice.
∙ Repeat the test with the ramp at 20cm, 30cm, 40cm, 50,cm, 60cm.
∙ Repeat the test three times for accuracy and repeat the experiment until the results are within 0.20 seconds of each other, so they are close and show reliability.
∙ Record the results in the following table:
∙ Use the equations above to fill in the following columns; Speed, Velocity2, and Potential energy.
Safety:
∙ Don’t use your hand to stop the car as it comes down the ramp as it may be fast enough to bruise.
∙ Make sure the ramp is safely secured by the clamp and that the clamp stand is steady so they do not collapse and cause injury.
∙ Do not press the stop clock to often because of repetitive strain injury.
Results:
Graphs:
Conclusion:
The height of the ramp which gave the fastest speed was 50 cm high which gave a sped of 1.79 metres per second. This is because potential energy is higher than other heights, and there is more to be transferred into kinetic energy. Gravity remains constant, but the steepness of the slope is different, higher. The steeper the slope means the potential energy is greater and the car moves faster.
The height of the ramp which gave the slowest speed was 10 cm high which gave a speed of 0.49 metres per second. This is because potential energy is lower than with the other heights, and there s less to be transferred into kinetic energy. Gravity remains constant but the steepness is different, smaller and lower down. Because the slope has the smallest angle the potential energy is lower and the car moves slower.
This means that the higher the ramp the greater the speed of the car. This is shown in the results which increase as the height of the ramp goes up to 50 cm. The lowest result is 0.49 m/s and the highest is 1.79 m/s, each are at either ends of the graph. There are results in between that continuously go up and do not drop down a mark, 0.89 m/s, 1.09 m/s, 1.31 m/s.
My results show a pattern, that as the height of the ramp increases the velocity of the car goes up. This is because potential energy is stored in the car and when the energy is transferred into kinetic energy the velocity grows.
The relationship between the speed and height is that both increase and decrease simultaneously. If height increases the speed will increase on the same scale. This is the same for potential energy and kinetic energy. They are directly proportional to each other. I observed that as the height increases the speed and/or velocity went up proportionally. By looking at the graphs it can be seen that the results are in roughly the same place, and in the same shape, which also shows that height and potential energy are almost directly proportional. This also means that for the marks to be in the same place the velocity2 and speed are almost directly proportional.
The last two results are close which could theoretically mean that if the results continued to be collected with the ramp higher than 60 cm the car would have reached its terminal velocity. But it could also mean that the timekeepers reaction time was their fastest, which causes inaccuracy in the results.
This can all be seen in the table and graph by looking at how close the last two results are, and that they suddenly increase from the 40 cm results.
I predicted: as the height of the ramp increases so does energy and speed and velocity. There would not be a terminal velocity because the ramp was too short for the car to reach a constant speed.
The height of the ramp does affect the speed of the car, and as the height increased the energy and speed and velocity also increases. The start of terminal velocity is visible in the last two results of the table/graph, but it is more visible in the graph.
My predictions for the graphs were fairly accurate, though in reverse. I predicted that the graph for speed and potential energy would have the marks go up at a constant rate and the marks on the height and velocity2 graph would even out, possibly to show terminal velocity. In actual fact, the graph for height and velocity2 go up at a constant rate and the graph for speed and potential energy evened out, possibly to show terminal velocity.
There was an anomalous result. This was the last result for just about every factor dealt with (i.e. speed, velocity). These results went down below the result before, which none of the other did. This could be due to either:
∙ the time keepers reaction time; the time keeper was working at their fastest reaction speed and could not move any faster.
∙ the car had reached its terminal velocity.
Evaluation:
My investigation was a fair experiment because:
∙ we did not change the car or the time keeper, or the ramp throughout the entire investigation.
∙ the weight and mass of the car remained the same.
∙ The experiment was not moved to a different location so there was no change in gravity.
∙ the ramp remained the same so that the length, texture and bounce would not change or affect the movement of the car.
∙ the height we raised the ramp was exactly the same each time.
But the following things caused the experiment to go wrong, this can be seen by the existence of an anomalous result. The reaction time of the time keeper was not fast enough and allowed us only to go as far as raising the ramp 60 cm. The vibrations of the car on the ramp made the ramp vibrate, which made the car turn slightly, stopping it from going in a straight line.
But these could have been amended by; doing a preliminary experiment to see who had the best reaction time, and use them for the time keeping, and holding the ramp down more steadily, also placing rubber mats at the bottom of the ramp and clamp stand to absorb the vibrations.
Our results were fairly close, this can be seen in the table, by the results for time taken being under 0.2 seconds away from each other.
The method did not tell us in great detail how to use the apparatus accurately. Repeating the experiment two more times may not have been enough to make the averages really close, accurate and reliable. We could improve this by writing it in more detail how to use the apparatus accurately. We could also use a longer ramp and more results after holding the ramp at 60 cm to see when the car is reaching terminal velocity. There were not enough ramp heights to completely confirm if the last results were showing terminal velocity or whether it was down to reaction time.
There are a few extension experiments that could be carried out:
1-) Do the experiment with a longer ramp.
2-) Re-do the experiment with the ramp releasing the car and recording the results using light-gates.
3-) To see the terminal velocity of the car, and that it has one.
4-) Re-do the experiment with another person for a different reaction time.
Extension Plan:
Aim:
The aim of this experiment is to see whether the weight of the car affects its speed as it is let down a ramp at different heights.
Method:
∙ Set up the apparatus as shown in the following diagram:
∙ Have three different cars the same size, but weighing; 0.8kg, 1.6kg, 2.4kg. They must be the same size so that the shape will not affect the speed at which they travel down the ramp, and it is the weight under investigation here, not the shape.
∙ Have the ramp to put at different heights; 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, 1m.
∙ Place the first car at the top of the ramp for the first height and set the timer to zero.
∙ Release the car and press ‘go’ simultaneously.
∙ Let the car come to a halt and press stop on the timer at the same time.
∙ Record the time taken.
∙ Repeat the test two more times. There should be three sets of results for accuracy. Make sure that all the results are at lease 0.2 seconds within each other so they are close and show reliability.
∙ Repeat the test with the ramp at 20cm, 30cm, 40cm, 50,cm, 60cm, 70cm, 80cm, 90cm, 1m.
∙ Repeat the previous steps with the other car weights; 0.8kg, 1.6kg, 2.4kg.
∙ Record the results in the following table:
