Answer:
Since there is no external force, there is no change (movement) in the center of mass. Internally, the center of mass might change position, but the external result is still zero net velocity.
The net recoil velocity must be zero.
Answer:
Explanation:
The acceleration due to gravity on earth is regardless of the mass of the object. This means, in the absence of air resistance, both a 3000 kg object and a 300 kg will accelerate at the same rate of towards earth.
The reason the acceleration due to gravity is the same for all masses is that by grace of nature, the inertial mass 
of the object from 
equals the gravitational mass from 
, resulting
which is the acceleration that only depends on the mass of earth and its radius, and not on the mass of the object.
Answer:
72000 miles
Explanation:
If the distance between the students is 600 miles, and this implies in a 3 degree difference in the sun position, that means this 600 miles is related to 3 degrees of the circunference of the planet.
So, to find the whole circunference of the planet, that is, 360 degrees, we just need to use a rule of three:
3 degrees -> 600 miles
360 degrees -> x miles
3x = 600 * 360
x = 600 * 360 / 3 = 72000 miles
