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3 years ago

12

Suppose you put an ice cube into a cup of hot tea. In what direction does energy in the form of heat flow? What happens to the i

ce cube as this flow of energy occurs?

1 answer:

Semenov [28]3 years ago

6 0

Answer:

The energy flows between the ice and the tea equally. The table below shows the temperatures of several different objects made of the same material.

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A microwave oven operating at 1.22 × 108 nm is used to heat 165 mL of water (roughly the volume of a teacup) from 23.0°C to 100.

ANTONII [103]

<u>Answer:</u> The number of photons are $3.7\times 10^8$

<u>Explanation:</u>

We are given:

Wavelength of microwave = $1.22\times 10^8nm=0.122m$ (Conversion factor: $1m=10^9nm$ )

To calculate the energy of one photon, we use Planck's equation, which is:

$E=\frac{hc}{\lambda}$

where,

h = Planck's constant = $6.625\times 10^{-34}J.s$

c = speed of light = $3\times 10^8m/s$

$\lambda$ = wavelength = 0.122 m

Putting values in above equation, we get:

$E=\frac{6.625\times 10^{-34}J.s\times 3\times 10^8m/s}{0.122m}\\\\E=1.63\times 10^{-24}J$

Now, calculating the energy of the photon with 88.3 % efficiency, we get:

$E=1.63\times 10^{-24}\times \frac{88.3}{100}=1.44\times 10^{-24}J$

To calculate the mass of water, we use the equation:

$Density=\frac{Mass}{Volume}$

Density of water = 1 g/mL

Volume of water = 165 mL

Putting values in above equation, we get:

$1g/mL=\frac{\text{Mass of water}}{165mL}\\\\\text{Mass of water}=165g$

To calculate the amount of energy of photons to raise the temperature from 23°C to 100°C, we use the equation:

$q=mc\Delta T$

where,

m = mass of water = 165 g

c = specific heat capacity of water = 4.184 J/g.°C

$\Delta T$ = change in temperature = $T_2-T_1=100^oC-23^oC=77^oC$

Putting values in above equation, we get:

$q=165g\times 4.184J/g.^oC\times 77^oC\\\\q=53157.72J$

This energy is the amount of energy for 'n' number of photons.

To calculate the number of photons, we divide the total energy by energy of one photon, we get:

$n=\frac{q}{E}$

q = 53127.72 J

E = $1.44\times 10^{-24}J$

Putting values in above equation, we get:

$n=\frac{53157.72J}{1.44\times 10^{-24}J}=3.7\times 10^{28}$

Hence, the number of photons are $3.7\times 10^8$

4 0

3 years ago

The info below shows three kettles with their powers and the time they take to boil 500cm3 of water. If electricity costs 9p per

Hitman42 [59]

The cost of boiling 500cm3 of water using the 3kW kettle is 1.35 P.

<h3>Cost of electricity for 3 kW kettle</h3>

The cost is calculated as follows;

1 unit = 9p /kWh

Total energy consumed by 3 kW kettle, E = P x t

where;

P is power (kW)
t is time in (hr)

E = 3 kW x (3 mins/60 mins/hr)

E = 0.15 kWh

Energy cost = 9 p/kWh x 0.15 kWh = 1.35 P

Thus, the cost of boiling 500cm3 of water using the 3kW kettle is 1.35 P.

Learn more about energy cost here: brainly.com/question/13795167

#SPJ1

5 0

1 year ago

You yell into a canyon. You hear the echo in 3 seconds. How long did the sound of your voice travel before bouncing off a cliff?

Lilit [14]

Answer:

The sound travelled 516 meters before bouncing off a cliff.

Explanation:

The sound is an example of mechanical wave, which means that it needs a medium to propagate itself at constant speed. The time needed to hear the echo is equal to twice the height of the canyon divided by the velocity of sound. In addition, the speed of sound through the air at a temperature of 20 ºC is approximately 344 meters per second. Then, the height of the canyon can be derived from the following kinematic formula:

$2\cdot h = v\cdot t$ (1)

Where:

$h$ - Height, measured in meters.

$v$ - Velocity of sound, measured in meters per second.

$t$ - Time, measured in seconds.

If we know that $v = 344\,\frac{m}{s}$ and $t = 3\,s$ , then the height of the canyon is:

$h = \frac{v\cdot t}{2}$

$h = \frac{\left(344\,\frac{m}{s} \right)\cdot (3\,s)}{2}$

$h = 516\,m$

The sound travelled 516 meters before bouncing off a cliff.

7 0

2 years ago

Jamie had a solid, angular crystal and noticed that it was very hard to break. Which model could represent the crystal?

VLD [36.1K]

Answer:

d

Explanation:

5 0

2 years ago

How are momentum and collision related?

Studentka2010 [4]

Answer:

im pretty sure a collision is a transfer of momentum.

Explanation:

hope this helps :)

5 0

3 years ago