A piece of substance of specific head capacity 450JKg-1K-1 falls through a vertical distance of 20m from rest. Calculate the rise in temperature of the substance on hitting the ground when all its energies are converted into heat. [g = 10ms-2]
A. 2/9°C B. 4/9°C C. 9/4°C D. 9/2°C
Correct Answer: B
Explanation
Energy at the height = mgh This energy is converted to heat energy - mcΔt ∴ From the principle of energy conversion, mcΔt = mgh m x 450 x Δt = m x 10 x 20 ∴ Δt = m x 10 x 20/(m x 450) = 200/450 = 4/9°C
