What is the mass of water used to cool the iron car engine?

In summary, the conversation discusses a 2.50 x 10^2 kg iron car engine that contains water as coolant. The engine was shut off at a temperature of 35 degrees Celsius and the air temperature was 10 degrees Celsius. The heat given off by the engine and the water as they cooled to the air temperature was calculated to be 4.4 x10^6 J. From this information, the question asks for the mass of water used to cool the engine. Using the formula Q = mc(tf-ti), the mass of water was calculated to be 15.0 kg.
  • #1
studenta
5
0
A 2.50 x 10^2 kg iron car engine contains water as coolant. Suppose the temperature of engine is 35 degree celcius when it shut off and air temperature is 10degree celcius. The heat given off by engine and watering it as they cool to air temperature is 4.4 x10^6 J. What is the mass of water used to cool engine?
 
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  • #2
You must make an attempt at solving the problem before help can offered. What formulas are relevant? What have you tried?
 
  • #3
gneill said:
You must make an attempt at solving the problem before help can offered. What formulas are relevant? What have you tried?

This is what i did:

Q for iron = mc(tf-ti)
= 2.50 x 10^2 kg x 450 J/kg/°c x (10°c - 35°c)
= -2.813 x 10^6 J

Q for water = 4.4 x10^6 J - 2.813 x 10^6 J
= 1.587 x10^6 J

mass for water = Q / c x (tf-ti)
= 1.587 x10^6 J / 4180 x ( 10°c - 35°c)
= 15.0 kg

Is it right?
 
  • #4
That looks fine.
 
  • #5


Based on the information provided, we can use the equation Q = mcΔT to solve for the mass of water used to cool the engine.

Q = heat given off by the engine and water as they cool to air temperature = 4.4 x 10^6 J
m = mass of water
c = specific heat of water = 4.186 J/g°C
ΔT = change in temperature = (35°C - 10°C) = 25°C

Plugging in the values, we get:
4.4 x 10^6 J = (m)(4.186 J/g°C)(25°C)
Solving for m, we get:
m = 4.4 x 10^6 J / (4.186 J/g°C)(25°C)
m = 2.11 x 10^4 g

Therefore, the mass of water used to cool the engine is 2.11 x 10^4 g or 21.1 kg.
 

1. What is specific heat?

Specific heat is the amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius (or one Kelvin).

2. How is specific heat different from heat capacity?

Specific heat is an intrinsic property of a substance, while heat capacity is an extensive property that depends on the mass and composition of a substance. In other words, specific heat is the amount of heat energy needed to raise the temperature of a unit mass of a substance, while heat capacity is the amount of heat energy needed to raise the temperature of a given sample of a substance.

3. Why do different substances have different specific heats?

Specific heat is dependent on the molecular structure of a substance. Different substances have different molecular structures and arrangements, which can affect how they interact with heat energy. For example, substances with stronger intermolecular forces tend to have higher specific heats because more energy is needed to break these forces and raise the temperature of the substance.

4. How is specific heat measured?

Specific heat is typically measured using a technique called calorimetry, which involves using a calorimeter to measure the heat exchanged between a substance and its surroundings. The specific heat can then be calculated using the formula Q = mcΔT, where Q is the heat energy, m is the mass of the substance, c is the specific heat, and ΔT is the change in temperature.

5. How does specific heat affect the temperature of a substance?

The specific heat of a substance determines how much heat energy is required to raise its temperature. Substances with higher specific heats require more heat energy to raise their temperature, while substances with lower specific heats require less heat energy. This means that substances with higher specific heats tend to have a more stable temperature, as they can absorb or release more heat energy without experiencing a significant change in temperature.

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