Question

Two forces act on an object as shown. Calculate the magnitude of the resultant force.[ Hint: Use the Pythagorean Theorem]

Answer 1

Using law of vector addition , the magnitude (R) of resultant force is given by

$\begin{gathered} R=\sqrt{30^2+40^2+2\times30\times40\sin90\degree;} \\ R=\text{ }\sqrt{4900}=\text{ 70N}\begin{cases}sin90\degree={1} \\ \end{cases} \end{gathered}$

Final answer is 70 N.

Note:- we need to use law of vector addition to get resultant of two forces but we cant use Pythagorean theorem for vector .