Answer
given,
mass of disk = 2 Kg
radius = 0.1 m
time = 10 sec
a) 800 rpm to rad/s
= ![800 \times \dfrac{2\pi}{60}](https://tex.z-dn.net/?f=800%20%5Ctimes%20%5Cdfrac%7B2%5Cpi%7D%7B60%7D)
= ![83.78\ rad/s](https://tex.z-dn.net/?f=83.78%5C%20rad%2Fs)
b) 740 rpm to rad/s
= ![740 \times \dfrac{2\pi}{60}](https://tex.z-dn.net/?f=740%20%5Ctimes%20%5Cdfrac%7B2%5Cpi%7D%7B60%7D)
= ![77.49\ rad/s](https://tex.z-dn.net/?f=77.49%5C%20rad%2Fs)
c) Angular acceleration
![\alpha = \dfrac{\omega_f - \omega_i}{t}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cdfrac%7B%5Comega_f%20-%20%5Comega_i%7D%7Bt%7D)
![\alpha = \dfrac{83.78 -77.49}{10}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cdfrac%7B83.78%20-77.49%7D%7B10%7D)
![\alpha =0.629\ rad/s^2](https://tex.z-dn.net/?f=%5Calpha%20%3D0.629%5C%20rad%2Fs%5E2)
d) moment of inertia of disc
![I = \dfrac{1}{2}mr^2](https://tex.z-dn.net/?f=I%20%3D%20%5Cdfrac%7B1%7D%7B2%7Dmr%5E2)
![I = \dfrac{1}{2}\times 2 \times 0.1^2](https://tex.z-dn.net/?f=I%20%3D%20%5Cdfrac%7B1%7D%7B2%7D%5Ctimes%202%20%5Ctimes%200.1%5E2)
I = 0.01 Kg.m²
e) τ = I α
τ = 0.01 x 0.629
τ = 6.29 x 10⁻³ N.m
f) impulse = Force x time
![J= \dfrac{\tau}{r}\times t](https://tex.z-dn.net/?f=J%3D%20%5Cdfrac%7B%5Ctau%7D%7Br%7D%5Ctimes%20t)
![J= \dfrac{6.29 \times 10^{-3}}{0.1}\times 10](https://tex.z-dn.net/?f=J%3D%20%5Cdfrac%7B6.29%20%5Ctimes%2010%5E%7B-3%7D%7D%7B0.1%7D%5Ctimes%2010)
J = 0.629 Ns
g) Work done
W = Δ KE
![W = \dfrac{1}{2}I(\omega_f^2-\omega_i^2)](https://tex.z-dn.net/?f=W%20%3D%20%5Cdfrac%7B1%7D%7B2%7DI%28%5Comega_f%5E2-%5Comega_i%5E2%29)
![W = \dfrac{1}{2}\times 0.01\times (83.78^2-77.49^2)](https://tex.z-dn.net/?f=W%20%3D%20%5Cdfrac%7B1%7D%7B2%7D%5Ctimes%200.01%5Ctimes%20%2883.78%5E2-77.49%5E2%29)
W = 5.07 J
Answer:
the second time there is a gas between you and the star,
Explanation:
When you observe the star for the first time you do not have a given between you and the star, therefore you observe the emission spectrum of the same that is formed by lines of different intensity and position that indicate the type and percentage of the atoms that make up the star.
When you observe the same phenomenon for the second time there is a gas between you and the star, this gas absorbs the wavelengths of the star that has the same energies and the atomisms and molecular gas, therefore these lines are not observed by seeing a series of dark bands,
The information obtained from the two spectra is the same, the type of atoms that make up the star
Answer:
![\alpha = 5.2 \times 10^{-5} per ^oC](https://tex.z-dn.net/?f=%5Calpha%20%3D%205.2%20%5Ctimes%2010%5E%7B-5%7D%20per%20%5EoC)
Explanation:
At room temperature the thickness of the film is just enough that it will cancel the reflected light
So here we will have
![2\mu t = \frac{\lambda}{2}](https://tex.z-dn.net/?f=2%5Cmu%20t%20%3D%20%5Cfrac%7B%5Clambda%7D%7B2%7D)
so we have
![t = \frac{\lambda}{4/mu}](https://tex.z-dn.net/?f=t%20%3D%20%5Cfrac%7B%5Clambda%7D%7B4%2Fmu%7D)
here we have
![\lambda = 582.3 nm](https://tex.z-dn.net/?f=%5Clambda%20%3D%20582.3%20nm)
![\mu = 1.750](https://tex.z-dn.net/?f=%5Cmu%20%3D%201.750)
now we have
![t = \frac{582.3 nm}{4(1.750)}](https://tex.z-dn.net/?f=t%20%3D%20%5Cfrac%7B582.3%20nm%7D%7B4%281.750%29%7D)
![t = 83.2 nm](https://tex.z-dn.net/?f=t%20%3D%2083.2%20nm)
now when temperature is increased to 177 degree C
then in this case we have
![\lambda_2 = 587.2 nm](https://tex.z-dn.net/?f=%5Clambda_2%20%3D%20587.2%20nm)
now we have
![t' = \frac{587.2 nm}{4(1.750)}](https://tex.z-dn.net/?f=t%27%20%3D%20%5Cfrac%7B587.2%20nm%7D%7B4%281.750%29%7D)
![t' = 83.89 nm](https://tex.z-dn.net/?f=t%27%20%3D%2083.89%20nm)
now we know by the formula of thermal expansion
![t' = t (1 + \alpha \Delta T)](https://tex.z-dn.net/?f=t%27%20%3D%20t%20%281%20%2B%20%5Calpha%20%5CDelta%20T%29)
![83.89 = 83.2(1 + \alpha(177 - 18.6))](https://tex.z-dn.net/?f=83.89%20%3D%2083.2%281%20%2B%20%5Calpha%28177%20-%2018.6%29%29)
![\alpha = 5.2 \times 10^{-5} per ^oC](https://tex.z-dn.net/?f=%5Calpha%20%3D%205.2%20%5Ctimes%2010%5E%7B-5%7D%20per%20%5EoC)
The answer is reveal urges and desires mask by the unconscious mind. According to Freud, Dreams reveal urges and desires mask by the unconscious mind. In terms of the unconscious. The purpose of dreams, as stated by Freud, is to fulfill repressed wishes through the process of dreaming, since they cannot be fulfilled in real life. .In our dreams, we can understand what it is what we want and desire, things that we might not be able to admit to ourselves while we are awake. Dreams also reveal our unconscious mind, the things we might want or need, but do not even realize ourselves.