Only two horizontal forces act on a 9.1 kg body. One force is 5.3 N, acting due east, and the other is 1.6 N, acting 56° north of west. What is the magnitude of the body's acceleration?

Answer 1

figure the acceleration in each direction.

a1=5.3/9.1 E

a2=1.6/9.1 in direction 53g NofW

You know the angle between, 180-56=124

Law of cosines:
magnitude acceleration^2=a1^2+a2^2-a1*a2*cos124