How Does Stirring Affect Water's Temperature Increase?

In summary, the question is asking for the change in thermal energy of 550 grams of water that is heated and stirred with 4e4 J of work. After the water's motion has dissipated, its temperature rises from 24°C to 75°C. The answer is 1.18e5 Joules, which can be found using the equation Delta E = W + Q = mC*(Delta Temp) where m is the mass of the water (550 grams), C is the specific heat capacity (4.7 J/g°C), and Delta Temp is the change in temperature (51°C). The solution provided by the online homework is showing the correct calculation for the change in thermal energy, which is 118000 Jou
  • #1
cowmoo32
122
0
Here's my question:
Suppose you warm up 550 grams of water (about half a liter, or about a pint) on a stove, and while this is happening, you also stir the water with a beater, doing 4e4 J of work on the water. After the large-scale motion of the water has dissipated away, the temperature of the water is observed to have risen from 24°C to 75°C.
What was the change in the thermal energy of the water?
The answer is 1.18e5 Joules

The equation is Delta E = W + Q = mC*(Delta Temp)
Solve for Q m=550 C=4.7 change in temp=51 and I'm guessing work is 4e4, but solving for Q using those numbers gives me 2.945 Joules. What am I messing up?
 
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  • #2
It sounds to me like you are misinterpreting the problem. Are you really being asked to find Q?
 
  • #3
yeah, it asks for the change in thermal engergy of the water and the only unkown I have is Q..

Here's the solution my online homework gave me:
http://img85.imageshack.us/img85/3900/screengi2.jpg
 
Last edited by a moderator:
  • #4
cowmoo32 said:
yeah, it asks for the change in thermal engergy of the water and the only unkown I have is Q..

Here's the solution my online homework gave me:
http://img85.imageshack.us/img85/3900/screengi2.jpg
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What does thermal energy of the water mean?
 
Last edited by a moderator:
  • #5
well, Delta E thermal for the water is change in the heat engergy of the water, which is Q, is it not?
 
  • #6
wait...i can't believe i didnt get this.

DeltaE = mC*DeltaT, and I have all of those
I still get 117810 and the answer is 118000..
 
  • #7
cowmoo32 said:
well, Delta E thermal for the water is change in the heat engergy of the water, which is Q, is it not?
In this case ΔE is not Q. The thermal energy of the water is increased by the heat added Q plus the work done by the beater W. That is what your online slolution/explanation is saying. But you are not being asked for Q, you are being asked for ΔE.
 

Related to How Does Stirring Affect Water's Temperature Increase?

1. What is thermal energy?

Thermal energy is the energy that comes from heat. It is the internal energy of a substance due to the motion and vibration of its particles.

2. How is thermal energy related to water?

Thermal energy and water are closely related because water is a good conductor of heat. This means that thermal energy can easily transfer from one object to another through water.

3. How does thermal energy affect the properties of water?

Thermal energy can change the physical state of water, such as turning it from a solid (ice) to a liquid (water) or a gas (water vapor). It can also affect the temperature of water, which plays a crucial role in weather patterns and ocean currents.

4. What is the importance of thermal energy in water systems?

Thermal energy is important in water systems because it helps regulate the temperature of bodies of water, which is essential for the survival of aquatic organisms. It also plays a role in the water cycle, as thermal energy is responsible for the evaporation and condensation of water.

5. How can thermal energy be harnessed from water?

Thermal energy can be harnessed from water in various ways, such as using it for geothermal energy production or using it to power steam turbines in a power plant. It can also be used for heating and cooling purposes in buildings through geothermal heat pumps.

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