Question

Temperature of 17

∘
C. It must be heated to a temperature of 83
∘
C in 3 minutes. Assume that 15.5% of the heat is lost in the process. (Specific heat capacity of water is 4179.6 J/kg/K) How much Heat Energy is required to heat the water sample? Give your answer in Joules. (3) How much Electrical Energy is required to heat the water sample? Give your answer in Joules. (3) How much electrical power P from the supply is required to heat the water sample? Give your answer in Watts. (2) How many units of electrical energy must come from the power supply to heat the water? Give your answer in kW⋅h.

Answer 1

To calculate the heat energy required to heat the water sample, we can use the formula:

Q = mcΔT

Where:

Q = heat energy

m = mass of the water sample

c = specific heat capacity of water

ΔT = change in temperature

Given:

Temperature change (ΔT) = 83°C - 17°C = 66°C

Loss of heat = 15.5% = 0.155

Calculating Heat Energy (Q):

First, we need to find the mass of the water sample. Let's assume it is 1 kg.

Q = mcΔT

Q = 1 kg * 4179.6 J/kg/K * 66°C

Q = 275,913.6 J

Therefore, the heat energy required to heat the water sample is 275,913.6 Joules.

Calculating Electrical Energy (E):

Since the question does not provide any information about the efficiency of the heating process, we assume that all the electrical energy is converted into heat energy.

E = Q

E = 275,913.6 J

Therefore, the electrical energy required to heat the water sample is 275,913.6 Joules.