Handout 6: Supporting pupil writing Investigating Craters
Aim You are going to investigate how the size of a crater is affected by the height from which the ‘meterorite’ is dropped. Method • collect a metre ruler, clamp stand, tray of sand and a metal ball • clamp the metre ruler in place above the sand • hold the ball against the ruler; start at 20cm • drop the metal ball into the sand. • measure depth of the crater • record the depth in the table • You should drop the ball from at least 5 different heights 20cm apart • The results for each drop height should be repeated 5 times. Results Depth of crater (mm)
Drop height (cm) set 1
Find the range and the mean: • the range is the smallest to largest values for each drop height (Eg 9-13cm) • the mean is the average: add the numbers together and divide by 5.
Graph Plot a graph of the results on graph paper, like the one below: Craters investigation
Crater depth (mm)
25 20 15 Series1 10 5 0 0
Drop height (cm)
• • • • •
set out the scales label the axes plot the points (use the mean values if you can) draw a line curve of best fit give it a title
Conclusion Describe any patterns in your graph; for example, how does the depth of the crater change as the height dropped is changed? Does the depth double if the height is doubled?
Explain in a scientific way, why the patterns in your graph are as they are.
Comment on the scatter in your results Was there a big range or a small range? Does this make you more sure or less sure about your results?
Evaluation Write some comments on how easy the experiment was to do. Could the procedure be improved in any way to give more accurate results?
How reliable is the data in your graph or results table? Are all results similar (= reliable) ? Or are they very different from each other (=less reliable?)
What might have caused the differences between the data in your experiment?
Suggest if the data is accurate and reliable enough to trust the Conclusion you wrote.
Extra information about craters: The height the ball is dropped from will determine its energy. The energy the ball has to start with due to its height above the ground is known as gravitational potential energy (GPE). This energy is changed into kinetic energy as the ball falls. Just as the ball lands, all of the energy has been changed into kinetic energy. So, if the ball is dropped from a greater height, it will impact with greater kinetic energy. This energy spreads into the sand as the ball lands. The speed of impact and the mass of the ball will together determine the force of impact - a greater speed of impact for the same ball would give a greater impact force.