Purpose: using simple apparatus investigate experimentally how the average speed of an object moving down a runway depends on the height of the runway.
The main variables in a science experiment are the independent variable, the dependent variable and the control variables.
The Independent Variable is what we change or control in the experiment.
The Dependent Variable is what we are testing and will be measured in the experiment.
The Control Variables are what we keep the same during the experiment to make sure it’s a fair test.
In this experiment the:
Remember - these variables are controlled (or kept the same) because to make it a fair test, only 1 variable can be changed, which in this case is the vertical height of the runway.
average speed =
As the height of the runway increases, the average speed of the marble will also increase.
Justification for the prediction
As the height of the runway increases the gravitational potential energy of the marble will also increase.
As the marble moves down the runway, its gravitational potential energy is converted to kinetic energy.
From the conservation of energy, the greater the amount of gravitational potential energy at the top, the greater the amount of kinetic energy at the bottom.
If the marble has greater amount of kinetic energy at the bottom of the runway, it will have greater speed.
This justifies the prediction that, average speed will increase as the vertical height of the runway increases.