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3 years ago

What is the equation for measuring the change in thermal energy?

Physics

1 answer:

Daniel [21]3 years ago

7 0

Answer:

Explanation: I think...

Thermal Energy formula Q = mcΔT

Q = Thermal Energy(J)

m = Mass(kg)

c = Specific Heat(J/kg°C)

ΔT = Change in Temperature(°C)

you have to write the equation based on what you are working on

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Newton's Law of Cooling states that the rate of cooling of an object is proportional to the temperature difference between the o

julsineya [31]

Answer:

1) $k=-\frac{1}{46}\approx -0.02$

2) $\textit{Limiting value} = 24$

3) $T(10)\approx \frac{494611944}{6436343}\approx 76.8$

Explanation:

First of all note that

$T_s=24$ is the surroundings temperature, the temperature of the room where the cup of coffee is. Then, the differential equation is:

$\frac{dT}{dt}=k(T-24)$

Also, note that all units are in degrees celsius and minutes. Then, we don't have to convert units. Let's not write units explicitly from now on.

Explanation

1) We have that

$\textit{rate of cooling}=\frac{dT}{dt}=1,\quad T=70$

at some point - the exact time at which this is true doesn't really play any role because the equation doesn't have t on the right hand side. Then, from the equation we get

$1=-(70-24)=46k\Rightarrow k=-\frac{1}{46}\approx -0.02$

The minus comes from considering the temperature must decrease. With this value we can write the equation more explicitely:

$\frac{dT}{dt}=-\frac{1}{46}(T-24)$

2) The coffee is cooling off as time goes by, and it won't get any cooler than 24 degrees celsius because that's the temperature of the room. Then, in the long run, the temperature of the coffee is 24 degrees celsius.

3) Remember that Euler's method consists of using an initial exact measurement to predict what will happen in the future, approximately. There is a formula to make those predictions an it depends on the time step they gave us. Let's compute things first and then I tell you the equations we used.

In this case we know that we start with a 90 degrees celsius cup of coffee, or, in terms of math,

$T(0)=90$

Then, we can predict:

$T(2)\approx 90+2\left[-\frac{1}{46}(90-24)\right]=\frac{2004}{23}\approx 87.1$

Let's use fractions so we don't lose accuracy from now. With this number we can make an approximation of the temperature after 2 more seconds:

$T(4)\approx \frac{2004}{23}+2\left[-\frac{1}{46}\left(\frac{2004}{23}-24\right)\right]=\frac{44640}{529}\approx 84.4$

and then

$T(6)\approx \frac{44640}{529}+2\left[-\frac{1}{46}\left(\frac{44640}{529}-24\right)\right]=\frac{994776}{12167}\approx 81.8$

and then

$T(8)\approx \frac{994776}{12167}+2\left[-\frac{1}{46}\left(\frac{994776}{12167}-24\right)\right]=\frac{22177080}{279841}\approx 79.2$

and finally, the number we wanted to find:

$T(10)\approx \frac{22177080}{279841}+2\left[-\frac{1}{46}\left(\frac{22177080}{279841}-24\right)\right]=\frac{494611944}{6436343}\approx 76.8$

I hope you noticed the pattern to compute the next prediction:

$\textit{next prediction} = \textit{previous one (or exact value if it's the first step)}\\+ h\ast(\textit{right hand side of the differential equation at the previous one})$

5 0

3 years ago

Sliding friction between two objects that are moving past each other can be increased by: a. putting sand between the objects b.

alukav5142 [94]

Answer:

Putting sand between the objects

Explanation:

Friction is the action of rubbing against an object, which can POSSIBLY create static electricity.

8 0

3 years ago

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What are some of the skills required to play floor hockey?

taurus [48]

Answer:

Skills required to play floor hockey include passing, receiving passes, shooting, stick- handling (dribbling), defensive skills and goaltending. Players are allowed to use both sides of the blade of the stick. The front side is called the forehand (face) and the back side is called the backhand.

4 0

2 years ago

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A 500 N force accelerates an object at 20 m s-2. What is its mass?

avanturin [10]

Answer: The mass of the object is 25kg.

The given question deals with Newton's second law of motion and its applications.

Explanation: Given force, F=500N

acceleration, a=20 m/ $s^{2}$

From Newton's 2nd law of motion , we have

F=ma where m=mass of the object

⇒500=m×20

⇒m=500/20=25

∴ Mass of the object is 25 kg .

Reference Link: brainly.com/question/1141170

#SPJ2

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1 year ago

Why transparent object don't form a shadow

Pani-rosa [81]

Explanation:

Transparent objects do not form shadows. The light passes completely from the transparent objects thus these objects will not form shadow. ... In such objects, the light gets refracted thus, such objects forms shadow. The refraction is also the reason why we can see such objects.

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2 years ago

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