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JAMB Physics 2023 Paper

Question : 42

Total: 65

0^{\circ}C

= 331 ms-1]

Solution:

Concept:

The speed of sound in air depends on temperature, so use the given

0\,{}^{\circ}\mathrm{C}

speed to find the actual speed at

-10.00\,{}^{\circ}\mathrm{C}

, then calculate the time from distance and speed.

Explanation:

Convert the air temperature to kelvin:

T = -10.00 + 273 = 263\ \mathrm{K}

The speed of sound at temperature

T

is:

v = 331\sqrt{\frac{T}{273}} = 331\sqrt{\frac{263}{273}}

Evaluate the speed:

v = 331 \times 0.9815 = 324.88\ \mathrm{m\,s}^{-1}

Use the relation

v = \frac{d}{t}

, so:

t = \frac{d}{v} = \frac{312}{324.88}

t = 0.960\ \mathrm{s}

Rounded to two decimal places,

t = 0.96\ \mathrm{s}

Answer:

0.96\ \mathrm{s}

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