A)The heating element of a water heater in an apartment building has a maximum p

Question

A)The heating element of a water heater in an apartment building has a maximum power output of 39 kW. Four residents of the building take showers at the same time, and each receives heated water at a volume flow rate of 12x10-5 m3/s. If the water going into the heater has a temperature of 15°C, what is the maximum possible temperature of the hot water that each showering resident receives?

B)Suppose a tank contains 665 m3 of neon (Ne) at an absolute pressure of 1.01×105 Pa. The temperature is changed from 293.2 to 294.4 K. What is the increase in the internal energy of the neon?

Explanation / Answer

power P = 39 kW = 39 * 10 ^ 3 W volume flow rate of each shower = 12 * 10 ^ -5 m^ 3/ s volume of water of four showers in 1 second V = 4 * 12 * 10 ^ -5 m^ 3 = 48 * 10 ^ -5 m^ 3 mass of water of volume V is m = V * 1000 kg / m^ 3 = 48 * 10 ^ -2 kg Initial temperature t = 15 oC we know P = mC ( t ' - t ) from this t ' = ( P /mC ) + t where C = specific heta of water = 4186 J / kg oC So, t ' = 19.4 +15 = 34.4 oC (B). volume V = 665 m^ 3 Pressure P = 1.01 * 10^ 5 Pa Initial temp T = 293.2 K Final temperature T ' = 294.4 K from the relation PV = nRT No.of moles n = PV / RT where R = gas constant = 8.314 J / mol K = 27553 moles So, increasein interna energy U = nCv* ( T ' - T ) where Cv = specific heat at constant volume = 1.5 R So, U = 412.336 * 10 ^ 3 J

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.