Two forces act on a particle: and

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

Two forces act on a particle:

\vec P=10\,\hat{i}+6\,\hat{j}\,\text{N}

and

\vec Q=-4\,\hat{i}+9\,\hat{j}\,\text{N}

. A third force

\vec R

of magnitude

R

makes an angle

\phi

with the positive x-axis such that the particle remains in equilibrium. Which of the following gives the correct values of

(R,\phi)

? (a)

21\,\text{N},\;248^{\circ}

(b)

16.2\,\text{N},\;68^{\circ}

(c)

16.2\,\text{N},\;248^{\circ}

(d)

16.2\,\text{N},\;112^{\circ}