Question

Four forces act on an object such that the object is at rest. Three of the forces are given by F₁ = 21-2j, F₂=i-4j, F4 = −3i-5j. Determine F3 and its magnitude.

Answer 1

$\vec F_1+\vec F_2+\vec F_4=-11\vec j,$

$\vec F_3=-\vec \Sigma=11\vec j.$