MCQ
A coin is placed on a horizontal platform which undergoes vertical simple harmonic motion of angular frequency $\omega $. The amplitude of oscillation is gradually increased. The coin will leave contact with the platform for the first time
  • A
    at the mean position of the platform
  • for an amplitude of $\frac{g}{\omega ^2}$
  • C
    for an amplitude of $\frac{g^2}{\omega ^2}$
  • D
    at the highest position of the platform

Answer

Correct option: B.
for an amplitude of $\frac{g}{\omega ^2}$
b
For block $A$ to move in $SHM.$

$\mathrm{mg}-\mathrm{N}=\mathrm{m} \omega^{2} \mathrm{x}$

where $x$ is the distance from mean position

For block to leave contact $\mathrm{N}=0$

$\Rightarrow m g=m \omega^{2} x \Rightarrow x=\frac{g}{\omega^{2}}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Three masses are placed on the $x-$axis $: 300\, g$ at origin, $500 \,g$ at $x = 40\, cm$ and $400\, g$ at $x = 70\, cm.$ The distance of the centre of mass from the origin is ....... $cm$
A rigid uniform bar $A B$ of length $L$ is slipping from its vertical position on a frictionless floor (as shown in the figure). At some instant of time, the angle made by the bar with the vortical is $\theta$. Which of the following statements about its motion is/are correct?

(image)

$[A]$ The midpoint of the bar will fall vertically downward

$[B]$ The trajectory of the point $\mathrm{A}$ is a parabola

$[C]$ Instantaneous torque about the point in contact with the floor is proportional to $\sin \theta$

$[D]$ When the bar makes an angle $\theta$ with the vertical, the displacement of its midpoint from the initial position is proportional to $(1-\cos \theta)$

A cubical block of side $30\,cm$  is moving with  velocity $2\,\,ms^{-1}$ on a smooth horizontal surface. The surface has a bump at a point $O$ as shown in figure. The angular velocity (in rad/s) of the block immediately after it hits the bump, is
A wheel of radius $R$ is trapped in a mud pit and spinning. As the wheel is spinning, it splashes mud blobs with initial speed $u$ from various points on its circumference. The maximum height from the centre of the wheel, to which a mud blob can reach is
A block of mass $10 kg$ is moving on a rough surface as shown in figure. The frictional force acting on block is ...... $N$
Equation of motion of a body is $\frac{d v}{d t}=-4 v+8$, where $v$ is the velocity in $m / s$ and $t$ is the time in second. Initial velocity of the particle was zero. Then,
Which of the following circular rods. (given radius $ r$ and length $l$ ) each made of the same material as whose ends are maintained at the same temperature will conduct most heat
A hockey player is moving northward and suddenly turns westward with the same speed to avoid an oopponent. The force that acts on the player is
The maximum and minimum distances of a comet from the Sun are $1.6 \times 10^{12}\, m$ and $8.0 \times 10^{10}\, m$ respectively. If the speed of the comet at the nearest point is $6 \times 10^{4}\, ms ^{-1},$ the speed at the farthest point is ......... $\times 10^{3}\, m / s$
A $1 \;kg$ stationary bomb is exploded in three parts having mass $1: 1: 3$ respectively. Parts having same mass move in perpendicular direction with velocity $30\; ms ^{-1}$, then the velocity of bigger part will be