A body of mass $8\,kg$ is hanging another body of mass $12\,kg$. The combination is being pulled by a string $T _2$ will be respectively: (use $g =9.8\,m / s ^2$ )
$240\,N , 96\,N$
$200\,N , 80\,N$
$220\,N ,90\,N$
$260\,N ,96\,N$
When $F =2 N$, the frictional force between 5 $kg$ block and ground is $..........\,N$
A block placed on a rough inclined plane of inclination $\left(\theta=30^{\circ}\right)$ can just be pushed upwards by applying a force " $F$ " as shown. If the angle of inclination of the inclined plane is increased to $\left(\theta=60^{\circ}\right)$, the same block can just be prevented from sliding down by application of a force of same magnitude. The coefficient of friction between the block and the inclined plane is
A force $\vec{F}=\hat{i}+4 \hat{j}$ acts on block shown. The force of friction acting on the block is
The pulleys in the diagram are all smooth and light. The acceleration of $A$ is $a$ upwards and the acceleration of $C$ is $f$ downwards. The acceleration of $B$ is