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3 years ago

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The student makes a single pile of the 500 sheets of paper. Which a metre rule, she measured the height of the pile. The height

of the pile is 0.048 m. Calculate the density of the paper.

1 answer:

Cerrena [4.2K]3 years ago

6 0

Answer: please see attached work.

Explanation: please see attached work. Assuming 500 sheets of paper = 20 lb. (typicical value).

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A car drives for 30 km with a speed of 30m/s. How much time does it take the car to travel this distance?

Artist 52 [7]

   Time = (distance) / (speed)

   = (30 km) / (30 m/s)

   = (30,000 m) / (30 m/s)

   = (30,000 / 30) sec

   =    1,000 seconds

   =    16 minutes 40 seconds

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3 years ago

What wavelength would a ripple in water have if the frequency is 1.8 Hz and a

Yuki888 [10]

Explanation:

825m/s / 1.8Hz = 458.33m

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2 years ago

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Suppose a sound wave and an electromagnetic wave have the same frequency. Which has the longer wavelength? 1. the electromagneti

Mashcka [7]

Answer:

1. the electromagnetic wave.

Explanation:

Mathematically,

wavelength = velocity ÷ frequency

A mechanical wave is a wave that is not capable of transmitting its energy through a vacuum. Mechanical waves require a medium in order to transport their energy from one location to another. A sound wave is an example of a mechanical wave. Sound waves are incapable of traveling through a vacuum.

Electromagnetic waves of different frequency are called by different names since they have different sources and effects on matter, increasing frequency decreases wavelength.

Sound waves (which obviously travel at the speed of sound) are much slower than electromagnetic waves (which travel at the speed of light.)

Electromagnetic waves are much faster than sound waves and If the Velocity of the wave increases and the frequency is constant, the wavelength also increases.

7 0

3 years ago

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 $3.7\times 10^8$

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3 years ago

A 60.0 kg person walks from the ground to the roof of a 74.8 m tall building.how much potential energy doed the person have at t

faust18 [17]

So first, we multiply mass by gravity by height, which is 60 * 9.8 * 74.8 = <span>43747.2

So the answer is: </span><span>43747.2

Hope this helped! c:</span>

5 0

3 years ago