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CAIE A-Level Physics 5.2.2 Gravitational Potential Energy Changes

Practise calculating gravitational potential-energy changes with delta EP = mg delta h, rearranging for unknowns and combining transfers with resistance.

Syllabus
2028–2030
Course
Physics 9702
Level
AS

Exam points

  • calculate gravitational potential energy changes using ΔEP = mgΔh in a uniform gravitational field
  • rearrange ΔEP = mgΔh to determine mass, height change or g
  • combine gravitational potential energy changes with other energy transfers, including work against resistance

5.2.2—The formula ∆EP = mg∆h for gravitational potential energy changes in a question 1

[Maximum number: 2]

A pendulum consists of a solid sphere suspended by a string from a fixed point P , as shown in Fig. 3.1.

Fig. 3.1 (not to scale)

Fig. 3.1 (not to scale)

The sphere swings from side to side. At one instant the sphere is at its lowest position X , where it has kinetic energy 0.86 J and momentum 0.72 Ns in a horizontal direction. A short time later the sphere is at position Y , where it is momentarily stationary at a maximum vertical height h above position X.

The string has a fixed length and negligible weight. Air resistance is also negligible.

Calculate height h.

h= m [2] \begin{aligned} & h= \\ & \text { m [2] } \end{aligned}
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