The temperature of the cooling water as it leaves the hot engine of an automobile is 240 °F. After it passes through the radiator it has a temperature of 175 °F. Calculate the amount of heat transferred from the engine to the surroundings by one gallon of water with a specific heat of 4.184 J/g °C.

Respuesta :

Answer:571.09 kJ

Explanation:

Given

Temperature of cooling water from engine exit[tex]=240^{\circ} F\approx 115.55^{\circ}C[/tex]

After Passing through the radiator its temperature decreases to [tex]175^{\circ}F\approx 79.44^{\circ}F[/tex]

specific heat of water[tex]=4.184 J/g^{\circ}C[/tex]

Volume of water [tex]= 1 gallon\approx 3.78 L[/tex]

density of water [tex]\rho =1 gm/mL[/tex]

Thus mass of water[tex]=\rho \times V=3.78\times 1=3.78 kg [/tex]

Heat transferred to the surrounding is equal to heat absorbed by cooling water

[tex]Q=m\cdot c\cdot \Delta T[/tex]

[tex]Q=3.78\times 4.184\times 1000\times (115.55-79.44)[/tex]

[tex]Q=3.78\times 4.184\times 1000\times (36.11)[/tex]

[tex]Q=571.09 kJ[/tex]

The amount of heat transferred from the engine to the surroundings by one gallon of water with a specific heat of 4.184 J/g °C is 572645.67 J

Heat: This can be defined as a form of energy that brings about the sensation of warmth. The S.I unit of heat is Joules (J)

The Question above can be solved using the formula below

Q = cm(t₁-t₂)............... Equation 1

Where Q  = amount of heat, c = specific heat capacity of water, m = mass of water, t₁ = initial temperature, t₂ = final temperature.

From the question,

Given: c = 4.184 J/g°C, m = 1 gallon  = 3785 g, t₁ = 240 °F = 115.56 °C, t₂ = 79.4 °C

Substitute these values into equation 1

Q = 4.184(3785)(115.56-79.4)

Q = 572645.67 J

Hence the amount of heat transferred from the engine to the surrounding is 572645.67 J

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