Specific Heat Capacity question - Help needed.

In summary, the two physics teachers are debating whether or not a drinks machine contains a reservoir of hot water. The first teacher believes that the water must come from the mains supply and be heated by a heater in the machine, while the second suggests that there is not enough room to store water inside the machine, and that the water must come from the mains supply and be heated by a heater in the machine. The teachers take the following measurements to decide who is correct: mass of water in the cup, room temperature, temperature of water in the cup, and time to fill the cup. The first teacher calculates that the mass of water in the cup is 0.20 kg, while the second teacher calculates that the mass of water
  • #1
nvidia17
8
0
I'm having a hard time getting my hear around this question. Help would be appreciated as my revision books are not helping. I'm not looking for answers (would be helpful) - just help that will actually be of use to me if I get this question in the real exam.

Two physics teachers are getting hot drinks from a drinks machine. One teacher suggests that the machine must contain a reservoir of hot water. The other reacher says that there isn't room to store water inside the machine. He suggests that the wter must cime from the mains water suply and be heated by a heater in the machine, as it is needed.

The teachers take the following measurements to decde who is correct.
  • Mass of water in cup = 0.20 kg
  • Room temperature = 22 °C
  • Temperature of water in cup = 75 °C
  • Time to fuill cup = 6.0 s
  • (Specific heat capacity of water = 4200 J kg¨¹ °C)

Calculate the energy required to heat the water for one cup.





Energy = .......
 
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  • #2
The drinks machine is marked "2500 W". Calculate the maximum thermal energy which the heater could supply in the time it takes to fill the cup.



Energy = .....
 
  • #3
What is your question, where to start? This is a very straightforward question if you have studied specific heat capacity. You have mass, you have heat capacity, you have a change in temperature, you want to calculate how much heat is reQuired. (That was a hint).
 
  • #4
The power supplied by the heater must equal the rate at which the heat or enthalpy of the water changes.

So write an equation which describes this relationship.
 
  • #5
Hi I need help with a question, I need to calculate the total amount of heat necessary to change .75kg of ice at -24*C into water at 107*C. {put heat into kcal}? I need help with this problem.
 

1. What is specific heat capacity and how is it measured?

Specific heat capacity is the amount of heat energy required to raise the temperature of one unit mass of a substance by one degree Celsius. It is measured in joules per kilogram per degree Celsius (J/kg°C) or in calories per gram per degree Celsius (cal/g°C). It can be measured experimentally by using a calorimeter and recording the temperature change of a substance when a known amount of heat energy is added.

2. What factors affect the specific heat capacity of a substance?

The specific heat capacity of a substance is affected by its chemical composition, density, and phase (solid, liquid, or gas). Substances with higher molecular complexity and stronger intermolecular forces tend to have higher specific heat capacities. The specific heat capacity also varies with temperature, with most substances having a higher specific heat at lower temperatures.

3. How does specific heat capacity relate to heat transfer?

Specific heat capacity is an important factor in heat transfer as it determines how much heat energy is required to change the temperature of a substance. Higher specific heat capacity means that a substance can hold more heat energy without changing its temperature significantly. This is why substances with higher specific heat capacities, such as water, are often used in cooling and heating systems.

4. How is specific heat capacity used in practical applications?

Specific heat capacity has many practical applications, including in cooking, heating and cooling systems, and insulation materials. For example, the specific heat capacity of water allows it to act as a heat reservoir, keeping our homes warm during colder months. It is also used in determining the amount of energy needed to cook food, and in selecting materials for insulation to minimize heat transfer.

5. Can the specific heat capacity of a substance change?

The specific heat capacity of a substance is an intrinsic property and does not change with the amount or size of the substance. However, it can vary slightly with temperature and pressure. It is important to note that specific heat capacity is different from heat capacity, which is the amount of heat energy required to change the temperature of a substance as a whole.

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