Practise Edexcel IGCSE Physics data analysis, communication and evaluation by drawing best-fit lines, spotting anomalies and judging conclusions.
Diagram 1 shows the apparatus a student uses to investigate the bending of a wooden strip.
Part of the wooden strip is clamped to a table.
A load is fixed to the free end of the wooden strip, causing it to bend.
Diagram 1
The free end of the wooden strip is positioned a length, L , beyond the edge of the table, as shown in diagram 1.
The weight of the load causes the end of the wooden strip to move down through a height, h.
A student investigates how the length, L , affects the height, h .
The table shows the results of the investigation.
Draw the curve of best fit.
The student concludes that h is directly proportional to L .
Evaluate the student's conclusion.
A student uses this apparatus to investigate how the efficiency of an electric motor varies with its input voltage.
This is the student's method.
- connect the electric motor to a d.c. power supply and a joulemeter
- attach a 1.0 kg mass to the electric motor using a length of string
- set the voltage of the power supply to 10 V and switch on the power supply
- switch off the power supply when the mass has been lifted through a distance of 50 cm
- record the input energy to the motor from the joulemeter
- calculate the energy transferred to the gravitational store of the mass
- calculate the efficiency of the motor
The student repeats this process, setting the power supply to a different voltage each time.
State how the student could improve the reliability of her results.
The table shows the student's results.
Draw a curve of best fit.