Let the unknown distance be xmiles
x/39-x/72=11hr
72x-39x/2808=11hr
33x/2808=11
33x= 30888
x=936miles
U can substitue back to check
at speed of 72mph, he would need 936/72=13hrs
at speed of 39mph, he would need 936/39=24hr
the difference is 24-13=11
To find the mass of the planet we will apply the relationship of the given circumference of the planet with the given data and thus find the radius of the planet. From the kinematic equations of motion we will find the gravitational acceleration of the planet, and under the description of this value by Newton's laws the mass of the planet, that is,
The circumference of the planet is,
Under the mathematical value the radius would be
Using second equation of motion
Replacing the values given,
Rearranging and solving for 'a' we have,
Using the value of acceleration due to gravity from Newton's law we have that
Here,
r = Radius of the planet
G = Gravitational Universal constant
M = Mass of the Planet
Therefore the mass of this planet is 
I'm pretty your it's magnetism though. Like magnets
Answer:
the objects in the universe are evenly placed. This means that a celestial object's gravity may not be able to attract another object. Another reason may be that the stars in solar systems act as points of equilibrium for the planets in the system. Take for example the sun. It maintains the position of the planets in the system and likewise the earth maintains the position of the moon. You can picture it as evenly placed atoms in matter and the subsequent electrons held by the nucleus
I think the missing word you're looking for here is 'unit'. The examples such as kilogram and gallons are all units of measurement. These are standard amounts used for mass, volume, and length. It is especially important to be consistent with this units especially when doing dimensional analysis.
