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Trava [24]
3 years ago
5

This chart lists four examples of two objects that are in contact.

Physics
1 answer:
Oxana [17]3 years ago
7 0

Before coming into conclusion first we have to understand the direction of heat flow.

Heat is the transferred thermal energy from one body to another body due to the temperature difference just like water flows from higher level to lower level.

Whenever two bodies having different temperature come closer to each other heat will flow from hotter body to cooler one if no external work is done. The heat flow may be through any of the ways i.e conduction,radiation or convection. Hence temperature difference is the parameter which gives the direction of heat flow.

The temperature is also considered as a measure of average kinetic energy of the substance.The thermal energy does not give the direction heat flow. Heat may  flow from the body  having low thermal energy but at higher temperature to the body having higher thermal energy but at low temperature. The reverse does not happen naturally .

In example 1 there is fire and air. Obviously fire is at high temperature and air at low temperature.So heat will flow from object 1 to object 2.

In example 2 there is a metal at 80 degree Celsius and another metal at 12 degree Celsius .So heat will flow from object 1 to object 2

In example 3 we have cooler ocean and warm air. So the heat will flow from object 2 to object 1.

In example 4 we have a tool with high thermal energy and a material with little thermal energy.We already know that thermal energy can not determine the direction of heat flow. Here the temperature of each substance is not given.The kinetic energy is  part of thermal energy.So there is the chance of higher kinetic energy of the tool for having higher thermal energy .At that time the heat will flow object 1 to object 2.Otherwise the reverse will occur. So it is a special case.

As per the question only option 4 is correct which tells that heat will flow from object 1 to object 2 in examples 1,2,4, and heat will flow from object 2 to 1 in example 3. Other options violate the fundamental law of thermodynamics.


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what is the energy (in eV units) carried by one photon violet light that has a wavelength of 4.5e-7?
DaniilM [7]
The energy of a photon is given by
E=hf
where h is the Planck constant and f is the photon frequency.

We can find the photon's frequency by using the following relationship:
f= \frac{c}{\lambda}
where c is the speed of light and \lambda is the photon's wavelength. By plugging numbers into the equation, we find
f= \frac{c}{\lambda}= \frac{3 \cdot 10^8 m/s}{4.5 \cdot 10^{-7} m}=6.67 \cdot 10^{14}Hz

And so now we can find the photon energy
E=hf=(6.6 \cdot 10^{-34} Js)(6.67 \cdot 10^{14}Hz )=4.4 \cdot 10^{-19} J

We know that 1 Joule corresponds to
1 J = 1.6 \cdot 10^{-19} eV
So we can convert the photon's energy into electronvolts:
E= \frac{4.4 \cdot 10^{-19} J }{1.6 \cdot 10^{-19} J/eV}=2.75 eV
4 0
4 years ago
What's the speed of a sound wave through water at 25° Celsius? A. 1,000 m/s B. 1,500 m/s C. 750 m/s D. 1,250 m/s
yan [13]
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5 0
3 years ago
There is a decrease in power. It can be concluded that there has also been a change in: A)current or voltage.
liraira [26]

A current or voltage

5 0
3 years ago
A pole that is 2.9m tall casts a shadow that is 1.32m long. at the same time, a nearby tower casts a shadow that is 37.75m long.
Mrrafil [7]
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Nothing to deal with physics.
Maths. Scale factor. Year 9.
5 0
4 years ago
Unless indicated otherwise, assume the speed of sound in air to be v = 344 m/s. A pipe closed at both ends can have standing wav
uranmaximum [27]

Answer:

68.8 Hz

137.6 Hz, 206.4 Hz

Explanation:

L = Length of tube = 2.5 m

v = Velocity of sound in air = 344 m/s

Distance between nodes is given by

L=\dfrac{\lambda}{2}+m\dfrac{\lambda}{2}\\\Rightarrow \dfrac{\lambda(n+1)}{2}=L\\\Rightarrow \lambda=\dfrac{2L}{n+1}

Where n = 0, 1, 2, 3, ...

Making n+1 = n

\lambda=\dfrac{2L}{n}

where n = 1, 2, 3 .....

For fundamental frequency n = 1

\lambda=\dfrac{2\times 2.5}{1}\\\Rightarrow \lambda=5\ m

Frequency is given by

f=\dfrac{v}{\lambda}\\\Rightarrow f=\dfrac{344}{5}\\\Rightarrow f=68.8\ Hz

The fundamental frequency is 68.8 Hz

First overtone

2f=2\times 68.8=137.6\ Hz

Second overtone

3f=3\times 68.8=206.4\ Hz

The overtones are 137.6 Hz, 206.4 Hz

4 0
4 years ago
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