Edexcel IGCSE Physics Handling Data

Two students do an experiment to determine their power when running up a set of steps.

The diagram shows how they set up their experiment. Not all of the steps are shown in the diagram.

This is the students' method.
- student A stands with a stopwatch at the top of the steps
- student A starts timing on the stopwatch and shouts "go" at the same time
- student B begins to run up the steps when she hears student A shout
- student A stops timing when student B reaches the top of the steps

The students repeat their method two more times.

There are 24 steps in total and each step has a height of 19 cm .

The table shows the times recorded for student B.

Calculate the mean time from this data.
Give your answer to three significant figures.

A teacher investigates the penetrating ability of the gamma rays from a gamma source.
This is the teacher's method.
- place the gamma source at a distance of 25 cm from a radiation detector
- place a 1 cm thick absorbing material between the source and the detector
- measure the radiation count from the source for a time period of 3 s
- calculate the count rate in counts per second
- repeat the measurement two more times

The teacher repeats this method for different absorbing materials.

The table shows the teacher's results for seven different absorbing materials.

Why is a bar chart the correct way to display the results?