A
feather ball thrown under the same conditions,
would produce a half unit of work, and the iron
ball, therefore, produced 800 times more energy.
RESISTANCE.--Now, in the movement of any body
through space, it meets with an enemy at every
step, and that is air resistance. This is much
more effective against the cotton than the iron
ball: or, it might be expressed in another way:
The momentum, or the power, residing in the
metal ball, is so much greater than that within the
cotton ball that it travels farther, or strikes a
more effective blow on impact with the wall.
HOW RESISTANCE AFFECTS THE SHAPE.--It is because
of this counterforce, resistance, that shape
becomes important in a flying object. The metal
ball may be flattened out into a thin disk, and now,
when the same force is applied, to project it forwardly,
it will go as much farther as the difference
in the air impact against the two forms.
MASS AND RESISTANCE.--Owing to the fact that
resistance acts with such a retarding force on an
object of small mass, and it is difficult to set up a
rapid motion in an object of great density, lightness
in flying machine structures has been considered,
in the past, the principal thing necessary.
THE EARLY TENDENCY TO ELIMINATE MOMENTUM.--
Builders of flying machines, for several
years, sought to eliminate the very thing
which gives energy to a horizontally-movable
body, namely, momentum.
Pages:
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33