Answer:
D. It is easy to copy.
Explanation:
It is not B, or A, nor C.
Answer:
2200000 = 2.2E6 min for light from Proxima to reach earth
8.3 min from light sun to reach earth
2.2E6/8.3 = 2.56E5 times for light from Proxima
Proxima is about 256,000 times farther away than the sun
Since the sun is about 93,000,000 = 9.3E7 miles from earth
Proxima is then 9.3E7 * 2.56E5 = 2.4E13 miles away
Note - the speed of light is
3.00E8 m/s * 60 s/min / 1000 m/km = 1.8E7 km/min as given
Answer:
Greater than
Explanation:
Here, angular momentum is conserved.

When the cloud shrinks under the right conditions, a star may be formed.
Thus, Diameter of clouds are much higher than a star.
Moment of inertia of cloud is greater than the star's inertial.
so, angular velocity of the star would be greater than angular velocity of the rotating gas.
Answer:
Explanation:
Given
mass of boy 
mass of girl 
speed of girl after push 
Suppose speed of boy after push is 
initially momentum of system is zero so final momentum is also zero because momentum is conserved




i.e. velocity of boy is 2.82 m/s towards west
Answer:
=20 turns
Explanation:
The given case is a step down transformer as we need to reduce 120 V to 6 V.
number of turns on primary coil N_{P}= 400
current delivered by secondary coil I_{S}= 500 mA
output voltage = 6 V (rms)
we know that

putting values we get


to calculate number of turns in secondary

therefore,
=20 turns