To solve the problem graphically, project each velocity on the
line joining the two points and combine the projections.
Construct the problem, and verify by the figiu'e the value ^=3.4.
Ex. 159. Two straight railways intersect at an angle of 60**. An
engine approaches the intersection on one of the tracks at the rate

of 25^, and on the other track an engine is leaving it at the rate

of 30i7. At what rate are the engines separating when each is
n

10 miles from the intersection?

Ex 160. (a) What is the acceleration of 10 lb. imder a force of
20poimdals?

(6) What is the acceleration of 1 kilogram under a force of
1,000,000 dynes?

Ex, 161. A mass weighs 1 oz. and is acted on by a force of 1 g.
Find the acceleration.
Ex. 162. (a) What is the acceleration of 1 ton xmder a force of
1000 lb.?

(6) What is the acceleration of 1 kilogram imder a force of 2000
djrnes?

Ex. 163. One poundal acts upon 1 g. What is the acceleration?

Ex. 164. One dyne acts upon 1 lb. What is the acceleration?

Ex. 165. A silver bar is 10 ft. long and its cross-section is 1 in.
square. A pressure at one end of the bar produces an acceleration

of 10— in the direction of its length. What is the stress at the

mid-section of the bar?

Take the bar as the axis of x, and construct a line whose ordi-
nate shall give the stress at the corresponding section of the bar.
