Edexcel iGCSE Physics -4.13 Gravitational Potential Energy- Study Notes- New Syllabus
Edexcel iGCSE Physics -4.13 Gravitational Potential Energy- Study Notes- New syllabus
Edexcel iGCSE Physics -4.13 Gravitational Potential Energy- Study Notes -Edexcel iGCSE Physics – per latest Syllabus.
Key Concepts:
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Gravitational Potential Energy
Gravitational potential energy (GPE) is the energy stored by an object because of its position in a gravitational field. When an object is lifted upwards, work is done against gravity and energy is transferred to its gravitational potential energy store.
Relationship Between GPE, Mass, Gravitational Field Strength and Height
The gravitational potential energy gained by an object is given by:
\( \mathrm{gravitational\ potential\ energy = mass \times gravitational\ field\ strength \times height} \)
\( \mathrm{E_p = mgh} \)
- \( \mathrm{E_p} \) = gravitational potential energy (joule, J)
- \( \mathrm{m} \) = mass (kilogram, kg)
- \( \mathrm{g} \) = gravitational field strength (newton per kilogram, N/kg)
- \( \mathrm{h} \) = vertical height (metre, m)
Near the surface of the Earth, \( \mathrm{g \approx 10\ N/kg} \) for IGCSE calculations.
Understanding the Equation
- A larger mass gains more gravitational potential energy.
- Greater height means more work done against gravity.
- A stronger gravitational field increases energy gained.
If any one of these quantities increases, the gravitational potential energy increases.
Energy Transfer Explanation
- Work is done when an object is lifted.
- Work done = energy transferred.
- The energy transferred becomes gravitational potential energy.
This links directly to the principle of conservation of energy.
Key Idea
- Gravitational potential energy depends on position.
- Lifting an object stores energy.
- Energy is transferred, not created.
Important Points to Remember
- Height must be vertical height, not distance along a slope.
- Use SI units only.
- GPE is zero at the chosen reference level.
Example
A box of mass \( \mathrm{4.0\ kg} \) is lifted vertically through a height of \( \mathrm{3.0\ m} \).
Calculate the increase in gravitational potential energy. (Take \( \mathrm{g = 10\ N/kg} \).)
▶️ Answer / Explanation
Use:
\( \mathrm{E_p = mgh} \)
\( \mathrm{E_p = 4.0 \times 10 \times 3.0} \)
\( \mathrm{E_p = 120\ J} \)
Example
An object gains \( \mathrm{500\ J} \) of gravitational potential energy when lifted through a height of \( \mathrm{5.0\ m} \).
Calculate the mass of the object. (Take \( \mathrm{g = 10\ N/kg} \).)
▶️ Answer / Explanation
Use:
\( \mathrm{E_p = mgh} \)
Rearrange:
\( \mathrm{m = \dfrac{E_p}{gh}} \)
\( \mathrm{m = \dfrac{500}{10 \times 5.0}} \)
\( \mathrm{m = 10\ kg} \)