An ultrasonic sensor in the cooling system of a high-temperature gas-cooled reactor emits a high-frequency sound wave of 85 kHz85\text{ kHz}85 kHz into a chamber containing helium gas at a temperature of 227∘C227^\circ\text{C}227∘C. The molar mass of helium is 4.0×10−3 kg mol−14.0 \times 10^{-3}\text{ kg mol}^{-1}4.0×10−3 kg mol−1.
The maximum displacement of the helium atoms from their equilibrium positions due to the ultrasonic wave is 3.2×10−8 m3.2 \times 10^{-8}\text{ m}3.2×10−8 m.
Determine:
The maximum speed vmaxv_{\text{max}}vmax of the oscillating helium atoms in the sound wave.
The root mean square speed cr.m.s.c_{\text{r.m.s.}}cr.m.s. of the helium atoms in the chamber (where the molar gas constant R=8.31 J mol−1 K−1R = 8.31\text{ J mol}^{-1}\text{ K}^{-1}R=8.31 J mol−1 K−1).
56 exam-style questions on OCR A A Level Physics Thermal physics, covering Temperature, Solid, liquid and gas, Thermal properties of materials, and Ideal gases. Each one has a worked solution and a mark scheme showing where the marks go.