Question

The coefficient of friction between two surfaces is ${\text{ }}\mu = {\text{ }}0.8.$ The tension in the string

(a) $0N$
(b) $4N$
(b) $6N$
(d) $8N$

Answer 1

Friction is the force that prevents solid surfaces, fluid layers, and material elements from sliding against each other. To answer the question, we'll look at the concept of friction force, which is a resistive force that works in the opposite direction of motion for a moving body.

Complete step by step answer:
It is given to us in the question that the coefficient of friction $\left( \mu \right) = 0.8$
The normal is moving upward, while the weight is moving downward.
Now, as we know that;
$F = \mu N = \mu mg\cos \phi$
So, putting the values in the equation;
\begin{array}{*{20}{l}} {F = 0.8 \times 1 \times 10 \times cos\left( {30} \right)} \\\ {F = 6.928{\text{ }}N} \end{array}
As a result, the frictional force is now acting in a downward direction.
$mg\sin \phi = 1 \times 10 \times \sin {30^ \circ } = 5N$
As a result, the downward force
$mg\sin \phi = F + T$
As we have found out the value of $mg\sin \phi$ , and $F$ so, we will find out the $T$ by simply putting all the values in the equation.
\begin{array}{*{20}{l}} {mg\sin \phi = F + T} \\\ {6.928 = 5 + T} \\\ {T = 0} \end{array}
We've assumed that the strain on the string is approximately zero.
Option (a) $0N$ is the right answer.

Additional Information:
Friction is desirable and necessary for providing traction and facilitating movement on land. For acceleration, deceleration, and changing direction, most ground vehicles rely on friction. Sudden traction loss can result in a loss of control and an accident.

Note:
Work done against friction is path dependent because friction is a non-conservative factor. Because some kinetic energy is always converted to thermal energy in the presence of friction, mechanical energy is not preserved.