Question

Figure shows a pair of pin jointed gripper tongs holding an object weighing $2000\text{N}$. The coefficient of friction $\mu$ at the gripping surface is $0.1$. $X-X^{\prime }$ is the line of action of the input force and $Y-Y^{\prime }$ is the line of application of normal gripping force. If the pin-joint is assumed as frictionless, the magnitude of force $F$ required to hold the weight (in $\text{N}$) is

Answer 1

From FBD, for the weight to be in equilibrium,
$2\mu N=2000$
$\Rightarrow N=\frac{1000}{0.1}=10000\text{N}$
Equating moments about the hinge
$F\times 30=N\times 15$
$\Rightarrow F=5000\text{N}$