skip to content

Darwin Correspondence Project

From G. H. Darwin   [c. 16 October 1873?]1

Dear Father,

If the impact of a weight falling on a horizontal plane is unity—the following table will give it for the other inclinations2

Inclination Impact

of plane to

horizon

0o. 1.

10o .9848 = 910 or 98100

20o .9397 = 910 or 94100

30o .8660 = 910 or 87100

40o .7660 = 810 or 76100 or 34

45o .7071 = 710 or 71100

50o .6428 = 610 or 64100 or 23

60o .5000 = 510 or 50100 or 12

70o .3420 = 310 or 34100 or 13

80o .1736 = 210 or 17100 or 16

90o 0

This may be epitomised thus, less to 40o the impact is about 910 at 40o it is 34, 45o it is 710, at 50o = 23, at 60o = 12, at 70o = 13 at 80o = 16 & at 90o of course 0o

Your affectionate Son | G H Darwin

Footnotes

The date is conjectured from the relationship between this letter and the letter from G. H. Darwin, 16 October 1873.
George’s letter may have to do with CD’s question about the angle a waxy leaf ought to hold to the horizon in order that raindrops should bounce off as completely as possible (letter to G. H. Darwin, 12 October [1873], and letter from G. H. Darwin, 16 October 1873).

Summary

Sends table showing relative force of impact of weight dropped on a plane inclined at different angles.

Letter details

Letter no.
DCP-LETT-9078
From
George Howard Darwin
To
Charles Robert Darwin
Sent from
unstated
Source of text
DAR 162: 62
Physical description
2pp

Please cite as

Darwin Correspondence Project, “Letter no. 9078,” accessed on 12 December 2017, http://www.darwinproject.ac.uk/DCP-LETT-9078

Also published in The Correspondence of Charles Darwin, vol. 21

letter