(i) Define bulk modulus of a fluid. (ii) Helium is often used to fill balloons…
PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
(i) Define bulk modulus of a fluid.
(ii) Helium is often used to fill balloons because it makes the human voice sound sharper than in ordinary air. Explain, with suitable reasoning based on fundamental properties of the two gases, why sound travels faster in helium than in air when both are at the same temperature.
(iii) A balloon is filled, one after the other, with helium and with carbon-dioxide at 300 K. Without performing any numerical calculation, predict in which filling the wavelength of a 1.0 kHz sound produced inside the balloon will be larger. Justify your answer clearly.