Question

The difference in the speeds of sound in air at $-5^{\circ }C,$ 60 cm pressure of mercury and ${30}^{\circ }C,$ 75 cm pressure of mercury is (velocity of sound in air at $0^{\circ }C$ is 332 m/s)

• A. 15.25 m/s
• B. 21.35 m/s
• C. 18.3 m/s
• D. 3.05 m/s

Answer 1

The correct option is B 21.35 m/s

Velocity of sound is not affected by the change in pressure of air. Velocity of sound at $1^{\circ }C,$
$v_1$ = (332+0.61 t)m/s
$At-5^{\circ }C,v_{-5^{\circ }C}=(332-0.61\times 5)m/s$
$At-{30}^{\circ }C,v_{{30}^{\circ }C}=(332-0.61\times 5)m/s$
$\therefore v_{{30}^{\circ }C}-v_{-5^{\circ }C}=(0.61\times 35)m/s$
= 21.35 m/s