South Bend news-times. (South Bend, Ind.) 1913-1938, 1919-01-04
Getting Away From The Earth
By Garrett II. Seryiss

Are we. after all. such prisoners
on our globe? Take a glass Of
water. Is not the force OF gravity
on the container? And the water
seeks its level Heat and light repei
gravity May we heed an undis-
covered force of locomotion-life
itself?-C. G. L."
Gravity Is not "a thing. 10 be re-
PEELED: IL is a force. TO be overcome.
There are many forces that can. and
do. overcome gravity. our muscular
force does that continually When
you lift weight. or go up a hill.
you overcome. or overmatch gravity.
If you could lift yourself By your
bcotstraps and keep on exercising
the same force continually. you
could lift yourself TO the moon.
So. too. if there were ladder
from the earth to the moon, and
your wind and muscular force held
out long enough. you could climb
up into the lunar world. And the
farther you got away from the earth
the less force Of gravity. or the less
weight you would have to contend
with.
At the distance of the moon
gravity would be so much reduced
that it would pull YOU back with
only i,S60OJh of the force with
which It pulls you on the earth.
That is. if on the earth's surface
your weight is 225 pounds. at the
distance of the moon il would be,
as far as the earth's gravity is con-
cerned. only one ounce But gravity,
although its force diminishes in
versely as the square of the dis
lance. never lets go altogether. You
would have to climb TO an infinite dis
lance before gravity would vanish.
Now. if the ladder l have mag
ined actually existed. then. as far
as the mere question OF overcoming
gravity is concerned. you could get
away from the earth. But, Of course.
there is no ladder and nothing
equivalent TO a ladder. You can go
up in the air to a certain limited
distance with the aid Of balloon.
or an aeroplane. so that, in a broad
sense. perhaps. you might liken the
atmosphere TO a ladder, but its ex-
tent is trifiing compared with the
diameter of the earth, TO say nothing
of interplanetary distances.
The only way in which you could
get free from the earth, outside the
atmosphere, would be by overcoming
the force of gravity permanently, and
you would have to do that at one
stroke, by starting with a velocity
which would continue forever TO ex-
coed the acceleration of gravity. OF
course you could neutralize gravity
if you had at command an equal
opposing force
A boy throws a ball straight up
into the air with a velocity suffi-
cient to overcome gravity for a GER
tain distance only The ball goes
slower and slower under the UNI
ceasing backward pull OF gravity
until it comes to rest. all the kinetic
energy with which it started having
been used in overcoming gravity up
to that point. But gravity continues
to pull after the bali stops rising.
and as the ball falls back under the
pull of gravity it picks up again the
Sinetic energy it had at the start.
Only in case the ball could be
started with a velocity sufficient TO
carry it against gravity to an infinite
distance could it be freed from the
| earth's control. This statement, of
course. excludes the effects OF the
| interference of other attracting
/ bodies besides the earth, such as the
sun. The required velocity. as /
have before stated. is about seven
| miles per second.
As to what forces might be en-
ployed 10 drive a body 10 an infinite
| distance. it is interesting to remark
| that much depends upon the size in
proportion 20 mass of the projected