An elementary treatise on kinematics and dynamics / by James Gordon MacGregor.

  • MacGregor James Gordon, 1852-1913.
Date:
1902
Catalogue details

Licence: In copyright

Credit: An elementary treatise on kinematics and dynamics / by James Gordon MacGregor. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    67] 67. Examples. (1) A railway train is moving with a speed of 20 mis. per hour, and is increasing its speed uniformly at the rate of 10 mls.-per-hour per hour. Find (a) its speed after 1| hours, and (b) the distance traversed in that time. [For (a)—Data: v0 = 20 mis. per hour; a = 10 mls.-per-hour per hour ; t=V5 hours. T.o be determined : v. And (63), v=v0+at. For (b)—Data: as above. To be determined: s. And (64), s= v0t + lat2.] Ans. (a) 35 mis. per hour ; (b) 41j mis. (2) A railway train, moving at 50 mis. per hour, has the brakes put od, and its speed diminishes uniformly for 1 minute, when it is found to have a speed of 20 mis. per hour. Find (a) its rate of change of speed, and (b) the distance traversed in the'time'.. Ans. (a) — 1,800 ml.-hour units ; (6) ^ ml. (3) A point whose speed is initially 20 m. per sec, aud is diminishing at the uniform rate of 50 cm.-per-sec. per sec, moves in its path until its speed is 120 m. per min. Find the length of path between the initial and final positions. [Data: v0 = 20 m. per sec; a= —50 cm.-per-sec. per sec.= —0'5 rn.-per-sec per sec.; •y = 120 m. per min. = 2 m. per sec. And (65), v2=v0i+2 as.] Aus. 396 m. (4) A point has a uniform rate of increase of speed of 20 cm.-per- sec per sec. and an initial speed of 30 cm. per sec. Find (a) the speed after 16 sec; (6) the time required to traverse 300 cm.; (c) the change of speed in traversing that distance. Ans. («) 350 cm. per sec.; (6) (n/129-3)/2 sec; (c) 10(\/l29-3) cm. per sec. (5) If in Ex. (4) the speed be decreasing instead of increasing, find (a) the distance from the starting'point to the turning point, (6) the distance from the starting point after 10 sec.; (c) the length of path traversed during the time in which the speed changes to 60 cm. per sec.; (d) the time required by the moving point to return to the starting point. [To find (a), note that the speed