(a) The gas of interstellar medium can be detected from the radiations of photons of wavelength 21 cm.
(b) The gas of interstellar medium can be detected from the absorption lines present in the light from distant stars, which must be caused by a medium of density and temperature other than that of the stars emitting the lights.
<h3>
What is interstellar medium?</h3>
Interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy.
<h3>Evidence that interstellar medium contains both gas and dust</h3>
- The gas of interstellar medium can be detected from the radiations of photons of wavelength 21 cm.
- The gas of interstellar medium can be detected from the absorption lines present in the light from distant stars, which must be caused by a medium of density and temperature other than that of the stars emitting the lights.
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Time taken by the bowling ball to reach its highest point= 0.214 s
initial velocity= Vi=2.1 m/s
Final velocity= Vf=0 as the velocity at the highest point is zero.
acceleration= g= -9.8 m/s²
using the kinematic equation Vf= Vi + at
0= 2.1 + (-9.8)t
t= -2.1/-9.8
t=0.214 s
Thus the time taken by the bowling ball to reach its highest point is 0.214 s
Answer:
853776 J
Explanation:
The work-energy needs to pump water out of the pool is the product of the weight of water and distance h
E = Wh = mgh
Since water mass is a body of water we can treat it as the product of density 1000kg/m3 and volume, which is the product of base area and uniform height h

Therefore:
![E = mgh = g\rho A\int\limits^{2.2}_0 {h} \, dh\\E = 9.8*1000*30*12[h^2/2]^{2.2}_0 = 1764000(2.2^2 - 0^2) = 853776 J](https://tex.z-dn.net/?f=E%20%3D%20mgh%20%3D%20g%5Crho%20A%5Cint%5Climits%5E%7B2.2%7D_0%20%7Bh%7D%20%5C%2C%20dh%5C%5CE%20%3D%209.8%2A1000%2A30%2A12%5Bh%5E2%2F2%5D%5E%7B2.2%7D_0%20%3D%201764000%282.2%5E2%20-%200%5E2%29%20%3D%20853776%20J)
Asteroids are too small to have atmospheres
Figure B. The second option.