What makes it possible for us to see the moon from earth?

How many photons will be required to raise the temperature of 1.8 g of water by 2.5 k ?'?

tatyana61 [14]

Missing part in the text of the problem:
"<span>Water is exposed to infrared radiation of wavelength 3.0×10^−6 m"</span>

First we can calculate the amount of energy needed to raise the temperature of the water, which is given by
$Q=m C_s \Delta T$
where
m=1.8 g is the mass of the water
$C_s = 4.18 J/(g K)$ is the specific heat capacity of the water
$\Delta T=2.5 K$ is the increase in temperature.

Substituting the data, we find
$Q=(1.8 g)(4.18 J/(gK))(2.5 K)=18.8 J=E$

We know that each photon carries an energy of
$E_1 = hf$
where h is the Planck constant and f the frequency of the photon. Using the wavelength, we can find the photon frequency:
$\lambda = \frac{c}{f}= \frac{3 \cdot 10^8 m/s}{3 \cdot 10^{-6} m}=1 \cdot 10^{14}Hz$

So, the energy of a single photon of this frequency is
$E_1 = hf =(6.6 \cdot 10^{-34} J)(1 \cdot 10^{14} Hz)=6.6 \cdot 10^{-20} J$

and the number of photons needed is the total energy needed divided by the energy of a single photon:
$N= \frac{E}{E_1}= \frac{18.8 J}{6.6 \cdot 10^{-20} J} =2.84 \cdot 10^{20} photons$

4 0

3 years ago

Explain why the elements of the same group exhibit the same chemical behavior

ElenaW [278]

Answer:

All the elements of a period have similar chemical properties because they have the same number of valence electrons in their outermost shell. Their atoms have the same number of electrons in the highest occupied energy level

4 0

3 years ago

A system releases 255 cal of heat to the surroundings while delivering 428 cal of work. what is the change in internal energy of

vichka [17]

Answer:-683 cal

Explanation:

Given

Heat released by system Q=-255 cal

as heat released is taken as negative and vice-versa

Work done by system W=428 cal

From First law of thermodynamics

$Q=\Delta +W , where \Delta U$ =change in internal Energy

$\Delta U=-255-428=-683$

7 0

3 years ago

What causes a objects to move or stay still? claim and evidence

jek_recluse [69]

Answer:

A force

Explanation:

A push or a pull is an example of a force and can cause an object to speed up, slow down, etc.. Newton's laws tell us that 1- an object will not change its motion unless a force acts on it 2- the force on an object is equal to its mass times its acceleration. 3- The third law states that for every action (force) in nature there is an equal and opposite reaction.. However, forces like gravity and friction can resist movement.

4 0

2 years ago

PLEASE HELP WILL MAKE BRAINIEST (GIVING AWAY 20 POINTS)

Bond [772]

1) The most potential energy is at position A

2) The most kinetic energy is at position C

Explanation:

1)

The gravitational potential energy is the energy possessed by an object due to its position in a gravitational field, and it is given by the equation

$PE=mgh$

where

m is the mass of the object

g is the acceleration of gravity

h is the height of the object relative to the ground

From the equation, we see that the potential energy is directly proportional to the heigth of the object: therefore, the roller coaster in this problem will have the most potential energy at its highest postion, so at position A.

2)

The total mechanical energy of the roller coaster at any point along the track is given by

$E=PE+KE$

where

PE is the potential energy

KE is the kinetic energy

Assuming there is no friction, the mechanical energy E is constant. This means that when PE increases, KE decreases, and when PE increases, KE decreases.

Therefore, the cart will have maximum kinetic energy when the potential energy is at minimum: and since the potential energy is directly proportional to the height of the track, this will occur at the lowest position, so at position C.

Learn more about kinetic and potential energy:

brainly.com/question/6536722

brainly.com/question/1198647

brainly.com/question/10770261

#LearnwithBrainly

5 0

3 years ago