The resultant of two forces P N and 3 N is a force of 7 N.

Question

The resultant of two forces $P$ N and $3$ N is a force of $7$ N. If the direction of the $3$ N force were reversed, the resultant would be $\sqrt{19}$ N. The value of $P$ is:

Accepted Answer

$R^2=P^2+Q^2+2PQ\cos\alpha$: $49=P^2+9+6P\cos\alpha$ \ldots (i); $19=P^2+9-6P\cos\alpha$ \ldots (ii)

Adding: $68=2P^2+18 \implies P^2=25 \implies P=5	ext{ N}$

Solutions · 1