Home » Archimedes archive » Acorn User » AU 1997-01 B.adf » Regulars » StarInfo/Allen/!Ignotum/Formulae/Formulae/Mech

StarInfo/Allen/!Ignotum/Formulae/Formulae/Mech

This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.

Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.

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# Maths > Mechanics

# New entries should take the form of:
#     Formula
#     Note 1
#     Note 2
#     Note 3
#     Note 4
#     Note 5
#     Formula
#     Note 1
#     And so on...
# To fit snugly into the window, each line should be no longer
# than 42 characters.
# There is a limit of 25 formulas per topic.

# Any notes should be made here, at the beginning and should
# be preceeded by a hash (#).

a.b=|a||b|cosx
The dot/scalar product:
a and b are two vectors
x is the angle between them


e=v2/v1
For two colliding objects:
e=coefficient of restitution
v2=speed of separation
v1=speed of approach

C=rsinx/x
For a circular arc of angle 2x:
C=distance of centre of mass from centre
r=radius


C=2rsinx/3x
For a circular sector of angle 2x:
C=distance of centre of mass from centre
r=radius


C=3h/4
For a solid cone:
C=distance of centre of mass from vertex
h=height of cone


C=2h/3
For a conical shell:
C=distance of centre of mass from vertex
h=height of cone


C=3r/8
For a solid hemisphere:
C=distance of centre of mass from plane
face
r=radius

C=r/2
For a hemispherical shell:
C=distance of centre of mass from plane
face
r=radius

MI=ml�/3
For a uniform rod, length 2l:
MI=moment of inertia about axis through
centre, perpendicular to length
m=mass

MI=mr�
For a uniform hoop, radius r:
MI=moment of inertia about axis through
centre perpendicular to plane
m=mass

MI=mr�/2
For a uniform disc, radius r:
MI=moment of inertia about axis through
centre perpendicular to plane
m=mass

MI=2mr�/5
For a uniform solid sphere, radius r:
MI=moment of inertia about the diameter
m=mass















































































00000000  23 20 4d 61 74 68 73 20  3e 20 4d 65 63 68 61 6e  |# Maths > Mechan|
00000010  69 63 73 0a 0a 23 20 4e  65 77 20 65 6e 74 72 69  |ics..# New entri|
00000020  65 73 20 73 68 6f 75 6c  64 20 74 61 6b 65 20 74  |es should take t|
00000030  68 65 20 66 6f 72 6d 20  6f 66 3a 0a 23 20 20 20  |he form of:.#   |
00000040  20 20 46 6f 72 6d 75 6c  61 0a 23 20 20 20 20 20  |  Formula.#     |
00000050  4e 6f 74 65 20 31 0a 23  20 20 20 20 20 4e 6f 74  |Note 1.#     Not|
00000060  65 20 32 0a 23 20 20 20  20 20 4e 6f 74 65 20 33  |e 2.#     Note 3|
00000070  0a 23 20 20 20 20 20 4e  6f 74 65 20 34 0a 23 20  |.#     Note 4.# |
00000080  20 20 20 20 4e 6f 74 65  20 35 0a 23 20 20 20 20  |    Note 5.#    |
00000090  20 46 6f 72 6d 75 6c 61  0a 23 20 20 20 20 20 4e  | Formula.#     N|
000000a0  6f 74 65 20 31 0a 23 20  20 20 20 20 41 6e 64 20  |ote 1.#     And |
000000b0  73 6f 20 6f 6e 2e 2e 2e  0a 23 20 54 6f 20 66 69  |so on....# To fi|
000000c0  74 20 73 6e 75 67 6c 79  20 69 6e 74 6f 20 74 68  |t snugly into th|
000000d0  65 20 77 69 6e 64 6f 77  2c 20 65 61 63 68 20 6c  |e window, each l|
000000e0  69 6e 65 20 73 68 6f 75  6c 64 20 62 65 20 6e 6f  |ine should be no|
000000f0  20 6c 6f 6e 67 65 72 0a  23 20 74 68 61 6e 20 34  | longer.# than 4|
00000100  32 20 63 68 61 72 61 63  74 65 72 73 2e 0a 23 20  |2 characters..# |
00000110  54 68 65 72 65 20 69 73  20 61 20 6c 69 6d 69 74  |There is a limit|
00000120  20 6f 66 20 32 35 20 66  6f 72 6d 75 6c 61 73 20  | of 25 formulas |
00000130  70 65 72 20 74 6f 70 69  63 2e 0a 0a 23 20 41 6e  |per topic...# An|
00000140  79 20 6e 6f 74 65 73 20  73 68 6f 75 6c 64 20 62  |y notes should b|
00000150  65 20 6d 61 64 65 20 68  65 72 65 2c 20 61 74 20  |e made here, at |
00000160  74 68 65 20 62 65 67 69  6e 6e 69 6e 67 20 61 6e  |the beginning an|
00000170  64 20 73 68 6f 75 6c 64  0a 23 20 62 65 20 70 72  |d should.# be pr|
00000180  65 63 65 65 64 65 64 20  62 79 20 61 20 68 61 73  |eceeded by a has|
00000190  68 20 28 23 29 2e 0a 0a  61 2e 62 3d 7c 61 7c 7c  |h (#)...a.b=|a|||
000001a0  62 7c 63 6f 73 78 0a 54  68 65 20 64 6f 74 2f 73  |b|cosx.The dot/s|
000001b0  63 61 6c 61 72 20 70 72  6f 64 75 63 74 3a 0a 61  |calar product:.a|
000001c0  20 61 6e 64 20 62 20 61  72 65 20 74 77 6f 20 76  | and b are two v|
000001d0  65 63 74 6f 72 73 0a 78  20 69 73 20 74 68 65 20  |ectors.x is the |
000001e0  61 6e 67 6c 65 20 62 65  74 77 65 65 6e 20 74 68  |angle between th|
000001f0  65 6d 0a 0a 0a 65 3d 76  32 2f 76 31 0a 46 6f 72  |em...e=v2/v1.For|
00000200  20 74 77 6f 20 63 6f 6c  6c 69 64 69 6e 67 20 6f  | two colliding o|
00000210  62 6a 65 63 74 73 3a 0a  65 3d 63 6f 65 66 66 69  |bjects:.e=coeffi|
00000220  63 69 65 6e 74 20 6f 66  20 72 65 73 74 69 74 75  |cient of restitu|
00000230  74 69 6f 6e 0a 76 32 3d  73 70 65 65 64 20 6f 66  |tion.v2=speed of|
00000240  20 73 65 70 61 72 61 74  69 6f 6e 0a 76 31 3d 73  | separation.v1=s|
00000250  70 65 65 64 20 6f 66 20  61 70 70 72 6f 61 63 68  |peed of approach|
00000260  0a 0a 43 3d 72 73 69 6e  78 2f 78 0a 46 6f 72 20  |..C=rsinx/x.For |
00000270  61 20 63 69 72 63 75 6c  61 72 20 61 72 63 20 6f  |a circular arc o|
00000280  66 20 61 6e 67 6c 65 20  32 78 3a 0a 43 3d 64 69  |f angle 2x:.C=di|
00000290  73 74 61 6e 63 65 20 6f  66 20 63 65 6e 74 72 65  |stance of centre|
000002a0  20 6f 66 20 6d 61 73 73  20 66 72 6f 6d 20 63 65  | of mass from ce|
000002b0  6e 74 72 65 0a 72 3d 72  61 64 69 75 73 0a 0a 0a  |ntre.r=radius...|
000002c0  43 3d 32 72 73 69 6e 78  2f 33 78 0a 46 6f 72 20  |C=2rsinx/3x.For |
000002d0  61 20 63 69 72 63 75 6c  61 72 20 73 65 63 74 6f  |a circular secto|
000002e0  72 20 6f 66 20 61 6e 67  6c 65 20 32 78 3a 0a 43  |r of angle 2x:.C|
000002f0  3d 64 69 73 74 61 6e 63  65 20 6f 66 20 63 65 6e  |=distance of cen|
00000300  74 72 65 20 6f 66 20 6d  61 73 73 20 66 72 6f 6d  |tre of mass from|
00000310  20 63 65 6e 74 72 65 0a  72 3d 72 61 64 69 75 73  | centre.r=radius|
00000320  0a 0a 0a 43 3d 33 68 2f  34 0a 46 6f 72 20 61 20  |...C=3h/4.For a |
00000330  73 6f 6c 69 64 20 63 6f  6e 65 3a 0a 43 3d 64 69  |solid cone:.C=di|
00000340  73 74 61 6e 63 65 20 6f  66 20 63 65 6e 74 72 65  |stance of centre|
00000350  20 6f 66 20 6d 61 73 73  20 66 72 6f 6d 20 76 65  | of mass from ve|
00000360  72 74 65 78 0a 68 3d 68  65 69 67 68 74 20 6f 66  |rtex.h=height of|
00000370  20 63 6f 6e 65 0a 0a 0a  43 3d 32 68 2f 33 0a 46  | cone...C=2h/3.F|
00000380  6f 72 20 61 20 63 6f 6e  69 63 61 6c 20 73 68 65  |or a conical she|
00000390  6c 6c 3a 0a 43 3d 64 69  73 74 61 6e 63 65 20 6f  |ll:.C=distance o|
000003a0  66 20 63 65 6e 74 72 65  20 6f 66 20 6d 61 73 73  |f centre of mass|
000003b0  20 66 72 6f 6d 20 76 65  72 74 65 78 0a 68 3d 68  | from vertex.h=h|
000003c0  65 69 67 68 74 20 6f 66  20 63 6f 6e 65 0a 0a 0a  |eight of cone...|
000003d0  43 3d 33 72 2f 38 0a 46  6f 72 20 61 20 73 6f 6c  |C=3r/8.For a sol|
000003e0  69 64 20 68 65 6d 69 73  70 68 65 72 65 3a 0a 43  |id hemisphere:.C|
000003f0  3d 64 69 73 74 61 6e 63  65 20 6f 66 20 63 65 6e  |=distance of cen|
00000400  74 72 65 20 6f 66 20 6d  61 73 73 20 66 72 6f 6d  |tre of mass from|
00000410  20 70 6c 61 6e 65 0a 66  61 63 65 0a 72 3d 72 61  | plane.face.r=ra|
00000420  64 69 75 73 0a 0a 43 3d  72 2f 32 0a 46 6f 72 20  |dius..C=r/2.For |
00000430  61 20 68 65 6d 69 73 70  68 65 72 69 63 61 6c 20  |a hemispherical |
00000440  73 68 65 6c 6c 3a 0a 43  3d 64 69 73 74 61 6e 63  |shell:.C=distanc|
00000450  65 20 6f 66 20 63 65 6e  74 72 65 20 6f 66 20 6d  |e of centre of m|
00000460  61 73 73 20 66 72 6f 6d  20 70 6c 61 6e 65 0a 66  |ass from plane.f|
00000470  61 63 65 0a 72 3d 72 61  64 69 75 73 0a 0a 4d 49  |ace.r=radius..MI|
00000480  3d 6d 6c b2 2f 33 0a 46  6f 72 20 61 20 75 6e 69  |=ml./3.For a uni|
00000490  66 6f 72 6d 20 72 6f 64  2c 20 6c 65 6e 67 74 68  |form rod, length|
000004a0  20 32 6c 3a 0a 4d 49 3d  6d 6f 6d 65 6e 74 20 6f  | 2l:.MI=moment o|
000004b0  66 20 69 6e 65 72 74 69  61 20 61 62 6f 75 74 20  |f inertia about |
000004c0  61 78 69 73 20 74 68 72  6f 75 67 68 0a 63 65 6e  |axis through.cen|
000004d0  74 72 65 2c 20 70 65 72  70 65 6e 64 69 63 75 6c  |tre, perpendicul|
000004e0  61 72 20 74 6f 20 6c 65  6e 67 74 68 0a 6d 3d 6d  |ar to length.m=m|
000004f0  61 73 73 0a 0a 4d 49 3d  6d 72 b2 0a 46 6f 72 20  |ass..MI=mr..For |
00000500  61 20 75 6e 69 66 6f 72  6d 20 68 6f 6f 70 2c 20  |a uniform hoop, |
00000510  72 61 64 69 75 73 20 72  3a 0a 4d 49 3d 6d 6f 6d  |radius r:.MI=mom|
00000520  65 6e 74 20 6f 66 20 69  6e 65 72 74 69 61 20 61  |ent of inertia a|
00000530  62 6f 75 74 20 61 78 69  73 20 74 68 72 6f 75 67  |bout axis throug|
00000540  68 0a 63 65 6e 74 72 65  20 70 65 72 70 65 6e 64  |h.centre perpend|
00000550  69 63 75 6c 61 72 20 74  6f 20 70 6c 61 6e 65 0a  |icular to plane.|
00000560  6d 3d 6d 61 73 73 0a 0a  4d 49 3d 6d 72 b2 2f 32  |m=mass..MI=mr./2|
00000570  0a 46 6f 72 20 61 20 75  6e 69 66 6f 72 6d 20 64  |.For a uniform d|
00000580  69 73 63 2c 20 72 61 64  69 75 73 20 72 3a 0a 4d  |isc, radius r:.M|
00000590  49 3d 6d 6f 6d 65 6e 74  20 6f 66 20 69 6e 65 72  |I=moment of iner|
000005a0  74 69 61 20 61 62 6f 75  74 20 61 78 69 73 20 74  |tia about axis t|
000005b0  68 72 6f 75 67 68 0a 63  65 6e 74 72 65 20 70 65  |hrough.centre pe|
000005c0  72 70 65 6e 64 69 63 75  6c 61 72 20 74 6f 20 70  |rpendicular to p|
000005d0  6c 61 6e 65 0a 6d 3d 6d  61 73 73 0a 0a 4d 49 3d  |lane.m=mass..MI=|
000005e0  32 6d 72 b2 2f 35 0a 46  6f 72 20 61 20 75 6e 69  |2mr./5.For a uni|
000005f0  66 6f 72 6d 20 73 6f 6c  69 64 20 73 70 68 65 72  |form solid spher|
00000600  65 2c 20 72 61 64 69 75  73 20 72 3a 0a 4d 49 3d  |e, radius r:.MI=|
00000610  6d 6f 6d 65 6e 74 20 6f  66 20 69 6e 65 72 74 69  |moment of inerti|
00000620  61 20 61 62 6f 75 74 20  74 68 65 20 64 69 61 6d  |a about the diam|
00000630  65 74 65 72 0a 6d 3d 6d  61 73 73 0a 0a 0a 0a 0a  |eter.m=mass.....|
00000640  0a 0a 0a 0a 0a 0a 0a 0a  0a 0a 0a 0a 0a 0a 0a 0a  |................|
*
00000680  0a 0a 0a 0a 0a 0a 0a 0a  0a 0a 0a                 |...........|
0000068b