Figure shows a man standing stationary with respect to a horizontal conveyor belt that is accelerating with $1\; m s^{-2}$. What is the net force on the man? If the coefficient of static friction between the man’s shoes and the belt is $0.2$, up to what acceleration of the belt can the man continue to be stationary relative to the belt? (Mass of the man $= 65 \;kg.)$
Mass of the man, $m=65\, kg$
Acceleration of the belt, $a=1 \,m / s ^{2}$
Coefficient of static friction, $\mu=0.2$
The net force $F$, acting on the man is given by Newton's second law of motion as:
$F_{m}=m a=65 \times 1=65\, N$
The man will continue to be stationary with respect to the conveyor belt until the net force on the man is less than or equal to the frictional force $f_{s}$, exerted by the belt, i.e., $F_{ na }^{\prime}=f_{s}$
$m a^{\prime}=\mu m g$
$\therefore a^{\prime}=0.2 \times 10=2\, m / s ^{2}$
Therefore, the maximum acceleration of the belt up to which the man can stand stationary is $2 \,m / s ^{2}$
A car is moving with uniform velocity on a rough horizontal road. Therefore, according to Newton's first law of motion
As shown in the figure, a block of mass $\sqrt{3}\, kg$ is kept on a horizontal rough surface of coefficient of friction $\frac{1}{3 \sqrt{3}}$. The critical force to be applied on the vertical surface as shown at an angle $60^{\circ}$ with horizontal such that it does not move, will be $3 x$. The value of $3x$ will be
$\left[ g =10 m / s ^{2} ; \sin 60^{\circ}=\frac{\sqrt{3}}{2} ; \cos 60^{\circ}=\frac{1}{2}\right]$
A heavy body of mass $25\, kg$ is to be dragged along a horizontal plane $\left( {\mu = \frac{1}{{\sqrt 3 }}} \right).$ The least force required is ........ $kgf$
For the given figure, if block remains in equilibrium position then find frictional force between block and wall ........ $N$
A block of mass $m$ is placed on a surface having vertical cross section given by $y=x^2 / 4$. If coefficient of friction is $0.5$ , the maximum height above the ground at which block can be placed without slipping is: