A protostar reaches equilibrium when gravity is balanced by the outward force of nuclear fusion.
Answer: the minimum spacing that must be there between two objects on the earth's surface if they are to be resolved as distinct objects by this telescope 6.45 cm
Explanation:
Given that;
diameter of the mirror d = 1.7 m
height h = 180 km = 180 × 10³ m
wavelength λ = 500 nm = 5 × 10⁻⁹ m
Now Angular separation from the peak of the central maximum is expressed as;
sin∅= 1.22 λ / d
sin∅ = (1.22 × 5 × 10⁻⁹) / 1.7
sin∅ = 3.588 × 10⁻⁷
we know that;
sin∅ = object separation / distance from telescope
object separation =
sin∅ × distance from telescope
object separation = 3.588 × 10⁻⁷ × 180 × 10³
object separation =6.45 × 10⁻² m
then we convert to centimeter
object separation = 6.45 cm
Therefore the minimum spacing that must be there between two objects on the earth's surface if they are to be resolved as distinct objects by this telescope 6.45 cm
Answer:

Explanation:
As we know,
=》Force = Mass × Acceleration
=》45 N = 0.75 × Acceleration
=》Acceleration = 45 ÷ 0.75
=》Acceleration = 60
hence, the Acceleration of the ball would be. 60 meters per second square

The weight of the shuttle is 
Explanation:
The weight of an object on Earth is the gravitational force exerted by the Earth on the object.
The magnitude of the weight of an object is given by:

where
m is the mass of the object
is the acceleration of gravity on Earth's surface
And the direction is downward (towards the Earth's centre).
For the shuttle in this problem, its mass is

So, its weight is

Note that while the mass of an object (m) does not change, its weight (W) changes according to the location, since the value of g can be different at different location (for example, on the Moon, the value of g is about 1/6 the value of g on the Earth).
Learn more about weight and forces:
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