In winter, the Neva is covered with ice 60 cm thick. The river is 65 km long and 300 m wide. How many cars of coal are needed
In winter, the Neva is covered with ice 60 cm thick. The river is 65 km long and 300 m wide. How many cars of coal are needed to completely melt the ice taken at the melting temperature. The car has a capacity of 50 tons of coal. density of ice 900 kg / m3 in a cube (m3). Specific heat of combustion is equal to 27 * 10 in the sixth power J / kg.
V = abh – ice volume
m = ρV = ρabh – ice mass
Q = mλ = m’q – heat balance
m ‘= mλ / q = ρabhλ / q – mass of coal
N = m ‘/ μ = ρabhλ / (μq) is the required number of cars
ρ = 900 kg / m³ – ice density
а = 65000 m – length of ice cover
b = 300 m – ice cover width
h = 0.6 m – ice cover thickness
λ = 330,000 J / kg – specific heat of ice melting
μ = 50,000 kg / wagon – wagon carrying capacity
q = 27,000,000 J / kg – specific heat of combustion of coal
N = 900 * 65000 * 300 * 0.6 * 330,000 / (50,000 * 27,000,000) = 2,574 cars (provided that all the heat from coal combustion goes to the melt of the ice cover of the Neva)
