On a winter day the temperature of the tap water is 20°C whereas the room temperature is 5°C. Water is stored in a tank of capacity 0.5 m3 for household use. If it were possible to use the heat liberated by the water to lift a 10 kg mass vertically, how high can it be lifted as the water comes to the room temperature? Take g = 10 m s–2.
Given:
Temperature of tap water=20⁰C
Room temp=5⁰C
Volume of tank=0.5m3
Mass to lift=10kg
Formula used:
ΔQ=MCΔT
ΔQ=heat exchange
ΔT=tempeature change
M=mass
C=heat capacity
Heat liberated by water =work done to lift
0.5× 1000× 4200× (20-5)=10× 10× height
Height=315000m=315km