A - A boy runs 12.7 blocks North, 7.5 blocks Northeast, and 14.4 blocks West. Determine the length of the displacement vector that goes from the starting point to his ﬁnal position.

Question

B -  Determine the direction of the displacement vector. Use counterclockwise as the positive angular direction, between the limits of −180◦ and +180◦ measured from East. Answer in units of ◦.

Henry · Answer

A. Disp. = 12.7[90o] + 7.5[45o] + 14.4[180o].
Disp. = 12.7i + (5.30+5.30i) - 14.4
Disp. = 18i - 9.1
Disp. = sqrt(9.1^2+18^2) =

B. Tan A = y/x = 18/(-9.1) = -1.97802.
A = -63.18o = 63.18o N. of W. = 116.8o CCW.