Answer:
Part a)
f = 1911.5 Hz
Part b)

Explanation:
Here the source and observer both are moving towards each other
so we know that the apparent frequency is given as

here we know that



now we will have


Part b)
Apparent wavelength is given by the formula

here we will have


Answer:
Explanation:
Expression for escape velocity
ve = 
ve² R / 2 = GM
M is mass of the planet , R is radius of the planet .
At distance r >> R , potential energy of object
= 
Since the object is at rest at that point , kinetic energy will be zero .
Total mechanical energy =
+ 0 = 
Putting the value of GM = ve² R / 2
Total mechanical energy = ve² Rm / 2 r
This mechanical energy will be conserved while falling down on the earth due to law of conservation of mechanical energy . So at surface of the earth , total mechanical energy
= ve² Rm / 2 r
Answer:4.05 s
Explanation:
Given
First stone is drop from cliff and second stone is thrown with a speed of 52.92 m/s after 2.7 s
Both hit the ground at the same time
Let h be the height of cliff and it reaches after time t

For second stone
---2
Equating 1 &2 we get





Answer:
Order of maximum transmission of the polarizer is A, C and B.
Solution:
As per the question:
For the first polarizer, the angle is quite insignificant:
(A)
:
The light intensity after passing through the first polarizer is
and this intensity does not depend on the angle of the polarizer.
Consider
with the vertical, the intensity is given by:

(B)
:
Suppose the second polarizer is
with the vertical.
Now, intensity through the second polarizer:


Now, if we consider the second polarizer to be
,

(C)
:
Now,
Intensity through the third polarizer, if it is
with the vertical:


Answer:
The distance between the earth and the star is increasing.
Explanation:
When we observe an object and its electromagnetic radiation has been displaced to blue, it means that it is getting closer to us, causing the light waves it emits to get closer together and its wavelength to decrease towards blue, this is knowm as blueshift.
On the contrary, when an object is rapidly moving away from us, the light waves or electromagnetic radiation it emits have been stretched from their normal wavelength to a longer wavelength, towards the red part of the spectrum. This is known as redshift.
This phenomenon of changes in wavelength and frequency due to movement (whether the source approaches or moves away) is described by the Doppler effect.
So for this case because the light we perceive from the star has moved to the red part of the visible spectrum, we can conclude that it is moving away from the earth, and that the distance between the star and the earth is increasing.