12.1 A geyser heats water flowing at the rate of 3.0 litres per minute from 27 °C to 77 °C. If the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat of combustion is 4.0 × 104 J/g?

 

It is given in the question that:

Rise in temperature of the water, ΔT = T2 – T1 = 77 – 27 = 50°C

Heat of combustion = 4 × 104 J/g

Specific heat of water, c = 4.2 J gm-1°C-1 

Mass of flowing water, m = 3.0 litre/min = 3000 g/min

Total heat used, ΔQ = mc ΔT = 3000 × 4.2 × 50 = 6.3 × 105 J/min

Rate of consumption =    6.3×1054×104 = 15.75 gm/min