Constant Acceleration
Yes. Neglecting the effects of air resistance, all objects near the surface of the earth fall with the same constant acceleration, regardless of their mass/weight.
mass = weight ÷ gravity Since the gravitational pull is relatively constant near the surface of the earth, you can weigh the object, then divide the weight by the gravitational acceleration (9.8 m/sec2 near the earth's surface).
In the same location, yes.
Gravity
Yes, relative to any observer not attached to the earth's surface.
Constant acceleration
No. It is an approximation for objects near earth, objects further away from earth experience less force and therefore dont have as great an acceleration.
Yes. Neglecting the effects of air resistance, all objects near the surface of the earth fall with the same constant acceleration, regardless of their mass/weight.
mass = weight ÷ gravity Since the gravitational pull is relatively constant near the surface of the earth, you can weigh the object, then divide the weight by the gravitational acceleration (9.8 m/sec2 near the earth's surface).
That depends on exactly what you mean. The Law of Universal Gravitation has "universal" in the name for a reason. It's the same on the Moon as it is on Earth, and the gravitational constant is identical there. However, the mass of the Moon is quite a bit less than the mass of the Earth. Countering that slightly, the Moon is also smaller than the Earth, meaning objects on its surface are closer to its center than objects on the Earth's surface are to the Earth's center. The net result is that the Moon's surface gravity is about one sixth that of the Earth.
man made objects cover about 32 % of the earth surface
In the same location, yes.
Gravity
Yes, relative to any observer not attached to the earth's surface.
Gainnkn kinetic energy
It depends on where you are. In most pars of space you are far away from any massive objects, so gravity will be much weaker than it is at Earth's surface. At the height of low Earth orbit, gravity is slightly less than it is at the surface. Only near very massive objects such as giant planets and stars will you experience stronger gravity than on Earth.
At the Earth's surface, the acceleration due to gravity is 9.8 m/s2.