The mass may weight 800 lbs on earth, but
now that no longer applies, and a man who
could only lift 100 to 150 lbs can now move it
The pull of gravity is equal to the square of the
distance between two objects and the
difference in proportion of there mass. So
resistance to movement afforded by gravity
and friction is stronger then the mass
resistance, but you still have Inertia from this
mass resistance, and you must use force to
accelerate or decelerate an object. There for if
you accelerate an object at a 1G rate, the
effects will be the same whether on earth or in
space, except it will take less force to do so in
There for the definition for Inertia that would
apply both to on earth and in space should be:
The resistance to changes in velocity, since
everything on earth is moving at a constant
So Newton's definition should be: The
tendency of a body to remain at rest (velocity)
unless acted upon by an external force, or for
the body to return to rest (velocity) unless
acted open by an external force.
Except in space where Inertia has no effect on
a body except during acceleration, and a body
moving at a constant speed will continue at its
velocity unless acted upon by an external force.
It's friction is dependent upon its shape and
the texture of the surface it rests on. The
smaller and lighter an object the less the
resistance, and a round object will make less
contact with a surface then a flat square
object. The round one will move easier by
rolling and have less resistance to the flow of
air around it. With the surface itself, if it is
smooth it has less resistance to an objects
movement then if it were rough.
The third factor Mass Resistance which is
caused by the fact that all mass has substance,
and even though an object may be removed
from the effects of the other two it will still
require force to move it.
There for Inertia (on earth ) is a resistance
equal to the sum of the mass resistance and
the victor between the inward pull of gravity,
and frictional drag in an opposite direction to
the applied force.
Some objects on a level plane, will continue to
move for a time after the initial force has been
applied. Such as a ball rolling, or a sled sliding
on ice, but they will eventually come to a stop
because of inertia, (resistance from these three
factors), unless further force is applied to
continue the motion.
Newton lived in a past era when man had not
yet stepped forth in to space, how could he
have known how a body would react out side
of the influence of earths gravity. Yet his laws
does apply in space removed from the
influence of gravity, and environmental friction.
Here a body accelerated to any given velocity
will continue to move with out any further
force applied, until it encounters an opposing
force. Here there is only the lesser resistance
of the quantity of mass to be moved, and we
must still exert force to move it.