\fdO'^ - Old Forge Coal Mines

ELEMENTARY MECHANICS. 175
(405) Use formulas 17 and 13. // = ^ ^ /' =
—^ X 3' = 144.72 ft., distance fallen at the end of third
second.
t; = ^/= 32.16 X 3 = 96.48 ft. per sec, velocity at end of
third second.
96.48 X 6 = 578.88 ft., distance fallen during the remain-
ing 6 seconds.
144. 72 + 578. 88 = 723. 6 ft. = total distance. Ans.
(406)
See Art. 961.
Striking force x :^ = 8 X 8 = 64. Therefore, striking
64
force = — = 1,536 tons. Ans.
2
12
(407)
(408)
See Arts. 901 and 902.
Use formula 19.
Centrifugal force = tension of string = .00034 WRN^ •—
.00034 X (.5236 X 4' X -261) x ^ X 60' = 13.38 + lb. Ans.
(409) (80' - 70') X . 7854 X 26 X . 261 X i = 3, 997. 2933 lb. ,
weight of one-half the fly-wheel
80- 10 . — .,.
,, ,,,, ^^
3o in., or \\ = 2}| ft.
rim. Inside radius =
According to formula 19, I^^= .00034 WR N^ =
.00034 X 3,997.2933 X 35 X 175' = 121,394+ lb. Ans.
12
(41 0) {a) Use formulas 1 1 and 12. Rid:; IV : zu, or
... wR 1x4,000 ,^,, A
"^= IT = -To5— = *" '"• ^"'-
'
(d) d' : R' ::IV: zu, or tv = ^ '
(411)
See Art. 955.
4 000' V 40
= ; ,,,^, 38.072 lb. Ans.
4,100