Sciences calculations

• Decomposition, or decay, is the breakdown of dead matter
• The rate of decay depends on:

  • Number of decomposing microorganisms
  • Temperature
  • Water and oxygen availability
• Rate changes show how quickly something is happening
• Rate of change can be calculated using the equation: rate of change = change in value / change in time
• To calculate the rate of change, we need to know the change from the previous point for each value
• Rate of change can also be calculated from graphs by finding the gradient of the trendline
• Equation for calculating rate of change from a graph: rate of change = vertical change / horizontal change
• The rate of change can be calculated by finding the gradient of the trendline on the graph
• Example calculation:

  • pH at 0 hours: 6.6
  • pH at 50 hours: 5.4
  • Rate of change = (5.4 - 6.6) pH units / (50 - 0 hours) = -0.024 pH units/hour
• Using the gradient of a graph to find a rate of change is easier when there is a lot of data or variability
• The greatest rate of change is shown in bold in the table provided