My aim in this experiment is to investigate how the compression of a spring affects the amount of kinetic energy transferred to the trolley that it is attached to.

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Emma Lerway                

Trolley Investigation


My aim in this experiment is to investigate how the compression of a spring affects the amount of kinetic energy transferred to the trolley that it is attached to.

Scientific Knowledge

In any compressed spring there is potential elastic energy. This can be calculated using the formula:

Elastic Energy = ½ k x 2 

When the spring is released it transfers the elastic energy mainly into kinetic energy. The formula that is used to calculate this energy is:

Kinetic energy = ½ m v 2

However to find the velocity of an object you must first calculate its speed. This is done using the formula:

Speed = Distance


In any case, the amount of elastic energy that an object has will affect the amount of energy transferred to kinetic energy. Inevitably if there is more elastic energy that means that there is a larger quantity that can be transferred, resulting in a bigger final amount of kinetic energy.


I will carry out my experiment in a safe, secure area so that no harm is caused to anyone or anything. Dangers that may be encountered during this investigation include the fast (or slow!) moving trolley, possibly causing damage to interfering obstacles or people. To ensure that this does not happen I will clear the area before carrying out the experiment.

I will ensure that people participating in the experiment are standing and not sitting and that a First aid kit is available in case of injury or emergency.

Preliminary Experiment

I carried out a simulation on a software package that had been installed on the computers at school. This allowed me to observe the way that my experiment should be carried out and also allowed me to obtain some preliminary results. These results will aid me with my prediction, indicating the type of trend my own results should present.

Although the computer simulation is very accurate in its measurements and readings, it is impossible for us to make up the exact same experiment that is shown on the screen, therefore our results will be very different. In this experiment, the trolley had a mass of 500g (the nearest to that of the trolley we will be using) and the length of the card 10cm (twice the length that we will be using). However, with this in mind, the following results were produced.

These results will be exceedingly accurate and as reliable as possible as they are generated on a computer. No anomalies have been found, and the results are considered almost perfect. Therefore this is a good foundation to structure my prediction on.


I will be using the following equipment in my investigation:

  • Trolley (with spring attached)
  • Ruler
  • Cardboard
  • Light Gate (connected to a computer)
  • Smooth surface
  • Calculator


The trolley will be adjacent to a wall, allowing the spring to compress against it. The light gate, position with a clamp, will be fixed directly above the trolley slightly away from the wall. There will be an upright strip of cardboard attached to the near front of the trolley which will pass through the light gate after the compression of the spring. I will then compress the spring at 1cm intervals and allow the trolley to pass through the light gate

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The light gate will measure how long the piece of cardboard on top of the trolley cuts the beam of light for, allowing me to calculate the speed using the formula:

Speed  =  Distance


I will then work out the amount of kinetic energy that has been transferred from the spring to the trolley, using the formula:

Kinetic energy = ½ m v 2

I will carry out the experiment three times for each compression ...

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