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jeyben [28]
3 years ago
15

Which list includes the phase changes that require a loss of energy (heat)?

Physics
1 answer:
Lemur [1.5K]3 years ago
3 0

Answer:

b  

Explanation:

because if you freeze somthing you do not gain heat you loss heat.

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Change in momentum is equal to force times the amount of time the force is applied? True or False?
harina [27]
The answer to this question is false
7 0
3 years ago
An electron in the n = 7 level of the hydrogen atom relaxes to a lower energy level, emitting light of 397 nm. what is the value
Dimas [21]

Answer:

n_f=2

Explanation:

It is given that,

Initially, the electron is in n = 7 energy level. When it relaxes to a lower energy level, emitting light of 397 nm. We need to find the value of n for the level to which the electron relaxed. It can be calculate using the formula as :

\dfrac{1}{\lambda}=R(\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2})

\dfrac{1}{397\times 10^{-9}\ m}=R(\dfrac{1}{n_f^2}-\dfrac{1}{(7)^2})

R = Rydberg constant, R=1.097\times 10^7\ m^{-1}

\dfrac{1}{397\times 10^{-9}\ m}=1.097\times 10^7\ m^{-1}\times (\dfrac{1}{n_f^2}-\dfrac{1}{(7)^2})

Solving above equation we get the value of final n is,

n_f=2.04

or

n_f=2

So, it will relax in the n = 2. Hence, this is the required solution.        

6 0
3 years ago
Read 2 more answers
What happens when you see something?
Elan Coil [88]
The answer is D light rays shine on an object which then reflects back to our retina
5 0
3 years ago
A starship travels to a planet that is 20 light years away. The astronauts stay on the planet for 2.0 years before returning at
ad-work [718]

Answer:

astronauts age is 32 years

correct option is e 32 years

Explanation:

given data

travels = 20 light year

stay = 2 year

return = 52 years

to find out

astronauts aged

solution

we know here they stay 2 year so time taken in traveling is

time in traveling = ( 52 -2 )  = 50 year

so it mean 25 year in going and 25 years in return

and distance is given 20 light year

so speed will be

speed = distance / time

speed = 20 / 25 = 0.8 light year

so time is

time = \frac{t}{\sqrt{1-v^2} }

time =  \frac{25}{\sqrt{1-0.8^2} }

time = 15 year

so age is 15 + 2 + 15

so astronauts age is 32 years

so correct option is e 32 years

4 0
3 years ago
Please do all of i will give you brainlest and thanks to best answer plz do it right
Sergeu [11.5K]

Answer:

winter solstice i think

Explanation:

8 0
3 years ago
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