The resultant of two forces,one double the other in magnitude,is perpendicular to the smaller of the two forces. The angle between the two forces is ........ $^o$

Write the condition for equilibrium when two forces act on a particle.

$P, Q$ and $R$ are three coplanar forces acting at a point and are in equilibrium. Given $P = 1.9318 \, kg \, wt$,$\sin {\theta _1} = 0.9659$,the value of $R$ is (in $kg \, wt$):

$A$ block of mass $90 \,kg$ is suspended by three strings $A, B$ and $C$ as shown in the figure. Find the tensions in the strings $A, B$ and $C$ respectively. $\left(g=10 \,ms^{-2}, \sin 37^{\circ}=0.6, \cos 37^{\circ}=0.8\right)$

$A$ stone of mass $0.05 \,kg$ is thrown vertically upwards. What is the direction and magnitude of the net force on the stone during its upward motion?

Two like parallel forces $20 \,N$ and $30 \,N$ act at the ends $A$ and $B$ of a rod $1.5 \,m$ long. The resultant of the forces will act at the point ........