Edexcel IGCSE Physics 4.14 Kinetic energy equation

Practise using KE = 1/2mv^2 for cars, particles, hammers and collisions, including rearranging for speed from kinetic energy.

Exam points

substitute mass and speed into KE = 1/2mv^2, using kg and m s^-1
rearrange KE = 1/2mv^2 to calculate speed from a stated kinetic energy
compare total kinetic energy before and after a collision to judge whether it is elastic

[Maximum number: 3]

A student uses a computer simulation to investigate the motion of particles in a gas.
He records the pressure of the gas and the mean speed of the particles in the gas at different temperatures.

The graphs show his results.

Graph 1

Graph 2

The student then calculates the kinetic energy of a single gas particle at each temperature.

The mass of a single gas particle is $5.3 \times 10^{-26} \mathrm{~kg}$ .

Calculate the average kinetic energy of a gas particle when the temperature of the gas is $100^{\circ} \mathrm{C}$ .

Marking points:
- recall of kinetic energy formula
- substitution
- evaluation

Example:
$\mathrm{KE}=\frac12\times\text{mass}\times\text{speed}^{2}$ $\mathrm{KE}=0.5\times5.3\times10^{-26}\times520^{2}$ $\mathrm{KE}=7.2\times10^{-21}\ \mathrm{J}$

Accept:
- ECF from part (i)
- $7.16\times10^{-21}$ to $7.31\times10^{-21}\ \mathrm{J}$

Marking guidance:
- power-of-ten error scores -1

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4.14 Kinetic energy equation question 1