Edexcel IGCSE Physics 4.13 Gravitational potential energy
Practise using GPE = mgh with masses, heights and g, including rearranging the equation and converting values into SI units.
- Syllabus
- First assessment 2019
- Course
- Physics 4PH1
Exam points
- substitute mass, g and height into GPE = mgh for lifted blocks, water or balls
- rearrange GPE = mgh to calculate mass or height from a stated energy change
- convert g to kg or cm to m before evaluating gravitational potential energy
4.13 Gravitational potential energy question 1
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.
Show that the gravitational store of the 1.0 kg mass increases by 5.0 J when it is lifted through a distance of 50 cm .
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