Question

A geyser heats water flowing at a rate of 2.0 kg per minute from 30°C to 70°C. If geyser operates on a gas burner, the rate of combustion of fuel will be __________ g min^–1.
[Heat of combustion = 8 × 10³ Jg^–1, Specific heat of water = 4.2 Jg^–1 °C^–1]

Answer 1

Correct Answer: 42

The correct answer is 42
\(Q = msΔT\)
\(\frac{dQ}{dt} = (\frac{dm }{dt})_{water}\)
\( SΔT = (\frac{dm}{dt})_{oil}C\)
\(⇒ 2 × 4.2 × 10³ × 40\) 
\(= (\frac{dm}{dt})_{oil} × 8 × 10^6\)
\(⇒ (\frac{dm}{dt})_{oil} = \frac{8 × 4.2 × 10^4}{8 × 10^6}  kg/minute\)
= 42 g/minute