Explanation:
Doppler's Effect: If a source is moving towards the observer the frequency of the waves emitted by the source will increase( wavelength will decrease). If the source is moving away from the observer the frequency of the waves emitted by the source will decrease( wavelength will increase). The best example of this is the changing frequency of siren of an ambulance as it moves towards us and then away from us.
The same phenomenon can be observed in celestial objects. When the object will move towards us the wavelength will decrease thus the spectrum will be shifted towards the blue part. This is known as blue shift.
If the object moves away from us the wavelength will increase and thus the spectrum will be shifted towards red part. This is know as Red-shift. This is because red has longer wavelength (620 - 750nm) than blue (450-495nm)
Thus if a galaxy shows us red-shifted spectra it means that it is moving away from us. we have observed this phenomenon in various galaxies thus supporting the expanding universe theory.
Answer:
1.9976 m
Explanation:
An iron bar whose initial length is 2m has its temperature increased from 20 ° C to 120 ° C. What is the final length of the bar? (consider that the coefficient of expansion of iron) is 1.2 x 10-5 1 / ° C (3 points)
Given that,
Initial length of an iron bar, 
The temperature increased from 20°C to 120°C
The coefficient of expansion of iron is 
We need to find the final length of the bar.
The linear expansion equation is given by :

Where
is the change in length

Also, 
L is final length

So, the final length of the bar is 1.9976 m
Answer:
The current in the circuit decrease slowly .
Explanation:
Given as :
For the electrical circuit
The voltage V in the circuit is slowly decreasing
The resistance R of the resistor slowly increasing after heating
Now, From Ohm's Law
Voltage is directly proportional to the flow of current through circuit
I.e V ∝ I
Or. V = R × I
where R is the proportionate constant and this is the resistance of the resistor
whose property is to opposes the flow of current in the circuit
So, If R value more then current I reduces in the circuit
∵ Here in the circuit , The resistance is slowly increasing, so, current I is slowly decreasing .
Hence The current in the circuit decrease slowly . answer
Answer:d
Explanation:
Given
First car is moving towards east with velocity 20 m/s

then it turns towards north then velocity is

suppose car takes t sec to change its path so average acceleration is given by


So average acceleration is towards North of west.
a) 1.57 m/s
The sock spins once every 2.0 seconds, so its period is
T = 2.0 s
Therefore, the angular velocity of the sock is

The linear speed of the sock is given by

where
is the angular velocity
r = 0.50 m is the radius of the circular path of the sock
Substituting, we find:

B) Faster
In this case, the drum is twice as wide, so the new radius of the circular path of the sock is twice the previous one:

At the same time, the drum spins at the same frequency as before, therefore the angular frequency as not changed:

Therefore, the new linear speed would be:

And substituting,

So, we see that the linear speed has doubled.