Answer:

Explanation:
We know that for circular motion the centripetal acceleration
is:

where v is the speed and r is the radius.
The centripetal acceleration for the astronaut must be the gravitational acceleration due to the gravity, as there are no other force. So
.
The radius of the orbit must be the radius of the Moon, plus the 270 km above the surface




We can obtain the speed as:






And this is the orbital speed.
I think it would be Newton’s second law
Answer:
Explanation:
Speed of an object is defined as the ratio of the distance covered by the object to the time taken to cover that distance.
Let
be the speed of the object.
Let
be the distance travelled by the object.
Let
be the time taken by the object.
So,
s=
So,the speed of the car is 
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