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4 years ago

8

If a person is planning to take a mixture of milk, cream and sugar and make it into ice cream do you expect the person to add or

remove heat energy

1 answer:

RideAnS [48]4 years ago

6 0

Remove (as he is going to put this mix into freezer)

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A laser used for many applications of hard surface dental work emits 2780-nm wavelength pulses of variable energy (0-300 mJ) abo

Bess [88]

Answer:

a

$n = 1.119 *10^{18} \ photons$

b

$P = 1.6 \ W$

Explanation:

From the question we are told that

The wavelength is $\lambda = 2780 nm = 2780 *10^{-9} \ m$

The energy is $E = 80 mJ = 80 *10^{-3} \ J$

This energy is mathematically represented as

$E = \frac{n * h * c }{\lambda }$

Where c is the speed of light with a value $c = 3.0 *10^{8} \ m/s$

h is the Planck's constant with the value $h = 6.626 *10^{-34} \ J \cdot s$

n is the number of pulses

So

$n = \frac{E * \lambda }{h * c }$

substituting values

$n = \frac{80 *10^{-3} * 2780 *10^{-9}}{6.626 *10^{-34} * 3.0 *10^{8} }$

$n = 1.119 *10^{18} \ photons$

Given that the pulses where emitted 20 times in one second then the period of the pulse is

$T = \frac{1}{20}$

$T = 0.05 \ s$

Hence the average power of photons in one 80-mJ pulse during 1 s is mathematically represented as

$P = \frac{E}{T}$

substituting values

$P = \frac{ 80 *10^{-3}}{0.05}$

$P = 1.6 \ W$

6 0

3 years ago

n the metric system the acceleration due to gravity near Earth's surface is about 9.81 meters per second per second. What is the

Anna007 [38]

Answer:

$32.2\frac{ft}{s^2}$

Explanation:

To do this conversion we have to know that:

$1ft=0.3048m$

(It is easy to find this value on physics textbooks or internet physics webpages)

So, we should convert the gravitational acceleration in the next way:

$9.81\frac{m}{s^{2}}=9.81\frac{m}{s^{2}}*\frac{1ft}{0.3048m}$

So, the meters cancel out:

$9.81\frac{m}{s^{2}}=9.81\frac{1}{s^{2}}*\frac{1ft}{0.3048}=32.18\frac{ft}{s^2}$

$9.81\frac{m}{s^{2}}=32.2\frac{ft}{s}$

3 0

3 years ago

Which of the following is not an example of accelerated motion

Leviafan [203]

An object moving at a constant speed.

7 0

3 years ago

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What is the specific heat of an unknown substance if 2000 J of energy are required to raise the temperature of 4 grams of the su

Dmitriy789 [7]

The energy required to heat a substance is related by the formula:
Q = mCpΔT ; where Q is the energy, m is the mass of the substance, Cp is the specific heat capacity and ΔT is the change in temperature.
2000 = (4)(Cp)(5)
Cp = 100 Joules / g °C

7 0

3 years ago

What would you use to stop itches from a bite

sukhopar [10]

You can use apple cider vinegar. If you don't have it, you can go to shoppers drug mart and they will have an ointment to sooth itches.

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3 years ago

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