Elementary mechanics
posted by david on .
(Q1) 2 forces act on a point object as follows: 100 at 170 and 100 at 50.Find the resultant force (a)110N at 50 (b)110N at 100 (c)100N at 110 (d) 100N at 50 (Q2) given 3 vectors a=i4j+2k,b=3i+2j2k,c=2i3j+k,Calculate a(bc) (a)6(b)6(d)9(d)9 (Q3)The resultant of vectors A and B has a magnitude of 20 units.A has a magnitude of 8 units,and the angle between A andB is 40. Calculate the magnitude of B. (a)12.6(b)16.2(c)14.8(d)18.4

F1 = 100[170o]
F2 = 100[50o]
X = 100*cos170+100*cos50o = 34.2 N.
Y = 100*sin170+100*sin50 = 94 N.
tan Ar = Y/X = 94/34.2 = 2.74838
Ar = 70o = Reference angle.
A = 70+180 = 110o
Fr = X/cosA = 34.2/cos110 = 100N.[110o]