A simple strategy is presented for solving the “inverse rocket” problem of a particle accumulating material from a medium through which it falls vertically. Some forms of drag can also be easily included, thereby changing the constant acceleration to a more realistic value.

1.
A. D.
Sokal
, “
The falling raindrop, revisited
,”
Am. J. Phys.
78
,
643
645
(
2010
).
2.
M. H.
Partovi
and
D. R.
Aston
, “
The generalized raindrop problem
,”
Am. J. Phys.
57
,
913
920
(
1989
).
3.
A similar observation applied to Eq. (8) divided by υβ in Ref. 1 suggests a change of dependent variable to p=mυ.
4.
B. F.
Edwards
,
J. W.
Wilder
, and
E. E.
Scime
, “
Dynamics of falling raindrops
,”
Eur. J. Phys.
22
,
113
118
(
2001
).
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.