Question

The maximum value of static friction is called limiting friction
A. True
B. False

Answer 1

As we all know that when we try to move a stationary block kept on a surface then it takes some effort to move the block as we have to overcome some resistance to move the block by increasing the effort applied.

Complete step by step answer:
As we can say that the term “static” is associated with the friction term so it definitely means that the body is at rest initially. This static friction comes to play when someone tries to move the block although the effort is applied, the block is not moving and hence the friction associated when there is no motion is called static friction.
The maximum value of static friction applied which tries to stop the block kept on the surface from moving is called Limiting friction.
Hence option (A) is correct and the statement is correct.
We can now say that when the applied force becomes more than limiting friction, then the body starts moving. Mathematically we can define it as
${f_s} \leqslant {f_L}$…… (I)
Here, ${f_s}$ is the static friction, and ${f_L}$ is the limiting friction.
From the above relation, it is clear that static friction can never be greater than limiting friction, it is basically the maximum value of static friction.
We can refer to the below figure to understand it better,

In the given figure, for the vertical equilibrium,
$N = mg$
Here $m$ is the mass of the block, $N$ is the normal reaction and $g$ is the acceleration due to gravity. While in the diagram $F$ is the applied force and ${f_s}$ is the static friction,
We also know that the value of the maximum value of friction ${f_{\max }}$ is given by,
${f_{\max }} = {\mu _s}N \\\ \Rightarrow {f_{\max }} = {\mu _s}mg \\\$
Here ${\mu _s}$ is the coefficient of static friction.

$\therefore$ The maximum value of static friction is limiting friction.

Note:
We should also make sure that when a body comes into motion, then also friction acts on it, hence it is equal to kinetic friction at this time The value of the coefficient of kinetic friction is always less than the coefficient of static friction.