DOC.
7
GRAVITATIONAL INDUCTION
129
A
+ a +
2a
=
M
+ m 
Mkm
.....(1a).
Rc2
In the second
case,
in which P alone
is
accelerated,
one
has,
according
to
the second
of
equations
(4)
and
according
to
(2),
/
=
«nr =
(«
+
or
a
=
m +
kmM
.....(2a).
Rc2
The third
case
yields,
analogously,
A
=
M
+
kmM
.....(3b)
Rc2
From
equations
(1a),
(2a),
and
(3a) we
obtain
3
kMm
a
=


2
Rc
2
In the
case
where
only
K is
accelerated,
but P is
kept
fixed,
the second
of
equations
(4)
assumes
the
form,
using
the value
of
a
that
was
just
found:
(k)=
3
kmM
r.
2
Rc2
k
is here the force that
must
be exerted
on
the
material
point
P
in order for it
to
remain
at
rest; thus,
(k) is the force exerted
(induced)
on
P
by
the
spherical
shell
K,
which
possesses
the acceleration
T.
This force has the
same
sign
as
the
acceleration,
in
contrast to the
corresponding
interaction
between
equivalent
electrical
masses.
[8]