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Question
How much heat energy is necessary to raise the temperature of 5 kg of water from 20°C to 100°C?
Solution
Given: Mass (m) = 5 kg, specific heat of water (c) = 1 kcal/kg °C
Change in temperature (ΔT) = 100 − 20 = 80°C
To find: Heat energy (Q)
Formula: Q = m c ΔT
Calculation:
According to the principle of heat exchange,
Energy supplied to water = Energy gained by water
From the formula,
Q = 5 × 1 × 80 = 400 kcal
Heat energy necessary to raise the temperature of the water is 400 kcal.
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