Question

The maximum and minimum magnitudes of the resultant of two forces are 17 newton and 7 newton respectively, if these two forces are acting at right angle to each other, then the value of resultant of these forces in netwon will be:

Answer 1

Let the forces be F1 and F2,
maximum force
$f1 + f2 = 17$
minimum force
$f1 - f2 = 7$

upon solving,
F1 = 12, F2 = 5
Thus when F1 & F2 are perpendicular to each other the the resultant force will be
$\sqrt{ {f1}^{2} + {f2}^{2} }$
$= \sqrt{ {12}^{2} + {5}^{2} } \\ = 13$
which is the required answer