QJEEM21Phf2d6: JEE Main 2021 Physics - Class 11 JEEM21Phf2d6 Solution: As shown in the figure, a block of mass 3 kg is kept on a…

Question

Verified Solution • 2025–26 Session moderate

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 3x. The value of x will be _________.

[g = 10 m/s²; sin60

^{\circ}

=

\frac{\sqrt{3}}{2}

; cos60

^{\circ}

=

\frac{1}{2}

]

Accepted Answer

N = Mg + Fsin60

^{\circ}

N =

\sqrt{3} g + \frac{F \sqrt{3}}{2}

For No slipping

Fcos60

^{\circ}

= Friction

\frac{F}{2} = μ N = \frac{1}{3 \sqrt{3}} (\sqrt{3} g + \frac{F \sqrt{3}}{2})

\frac{F}{2} = \frac{g}{3} + \frac{F}{6}

\frac{F}{2} - \frac{F}{6} = \frac{g}{3}

\frac{6 F - 2 F}{12} = \frac{g}{3}

4F = 4g

F = 10

F = 3x

x =

\frac{F}{3}

=

\frac{10}{3}

= 3.33

x = 3.33

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