CAIE IGCSE Physics Complex Energy Conservation

Practise constructing multi-stage energy balances with kinetic, gravitational and dissipated energy and extracting useful or wasted values from Sankey diagrams.

Exam points

write an energy balance containing kinetic, gravitational and work against resistance
rearrange the balance to find a speed, acceleration, work done or dissipated energy
read a Sankey diagram scale and combine the branches representing wasted energy

[Maximum number: 1]

The diagram shows an object of mass m being projected with speed v from a point P to a point Q on top of a cliff height h.

The object does work W against air resistance as it travels from P to Q.

Figure for Question 1.7.1.6—Principle of the conservation of question 1 — CAIE IGCSE Physics

What is the kinetic energy of the object when it reaches point Q ?

$\frac{1}{2} m v^{2}+m g h+W$

$\frac{1}{2} m v^{2}+m g h-W$

$\frac{1}{2} m v^{2}-m g h+W$

$\frac{1}{2} m v^{2}-m g h-W$

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1.7.1.6—Principle of the conservation of question 1