Answer:
The velocity of the arrow after 3 seconds is 30.02 m/s.
Explanation:
It is given that,
An arrow is shot upward on the moon with velocity of 35 m/s, its height after t seconds is given by the equation:

We know that the rate of change of displacement is equal to the velocity of an object.

Velocity of the arrow after 3 seconds will be :

So, the velocity of the arrow after 3 seconds is 30.02 m/s. Hence, this is the required solution.
Answer : Yes, distance measurements based on the speed of light used for objects in space.
Explanation : A light year is measurement of distance that light travel in a one year.
In a one year light travels 9460000000000 kilometer.
We know that, speed of light is 
and time is 31536000 seconds in 1 year
so, distance = speed of light X time
Now, the light year is 
Example : The nearest star to earth is about 4.3 light year away.
Answer:

Explanation:
At some distance from the Earth the force of attraction due to moon is balanced by the force due to Moon
so we will have

now we have


so we will have

Now by energy conservation


