MCQ
A man weighing $60\, kg$ stands on the horizontal platform of a spring balance. The platform starts executing simple harmonic motion of amplitude $0.1\, m$ and frequency $\frac{2}{\pi }Hz$. Which of the following statement is correct
  • A
    The spring balance reads the weight of man as $60\, kg$
  • B
    The spring balance reading fluctuates between $60\, kg$. and $70 \,kg$
  • C
    The spring balance reading fluctuates between $50\, kg$ and $60\, kg$
  • The spring balance reading fluctuates between $50\, kg$ and $70\, kg$

Answer

Correct option: D.
The spring balance reading fluctuates between $50\, kg$ and $70\, kg$
d
(d) The maximum force acting on the body executing simple harmonic motion is

$m{\omega ^2}a = m \times {(2\pi f)^2}a = 60 \times {\left( {2\pi \times \frac{2}{\pi }} \right)^2} \times 0.1\,N$

$ = 60 \times 16 \times 0.1 = 96N = \frac{{96}}{{9.8}} \approx 10\,kgf$ and this force is towards mean position.

The reaction of the force on the platform away from the mean position. It reduces the weight of man on upper extreme i.e. net weight $= (60 -10)\, kgf.$

This force adds to the weight at lower extreme position i.e. net weight becomes $= (60 + 10)\, kgf.$

Therefore, the reading the weight recorded by spring balance fluctuates between $50\, kgf$ and $70\, kgf.$

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

If masses of two point objects are tripled and distance between them is doubled, then gravitational force of attraction between them will .......... $\%$
A driver takes $0.20s$ to apply the brakes after he sees a need for it. This is called the reaction time of the driver. If he is driving a car at a speed of $54km/ h$ and the brakes causes a deceleration of $6.0 m/ s^2$, find the distance traveled by the car after he sees the need to put the brakes on.
In projectile motion, the modulus of rate of change of velocity
$Assertion :$ A hollow metallic closed container maintained at a uniform temperature can act as a source of black body radiation.
$Reason :$ All metals act as black bodies.
The time period of a satellite of earth is $5\, hours$. If the separation between the centre of earth and the satellite is increased to $4\, times$ the previous value, the new time period will become ....... $h$
A simple pendulum executing $S.H.M.$ is falling freely along with the support. Then
The angular velocity of the earth at present in $\omega $ . With what angular velocity should it rotate so that weight of body at the equator appears to be zero ? ....... $\omega $
The potential energy of a molecule on the surface of a liquid compared to one inside the liquid is
A uniform chain of $6\, m$ length is placed on a table such that a part of its length is hanging over the edge of the table. The system is at rest. The co-efficient of static friction between the chain and the surface of the table is $0.5$, the maximum length of the chain hanging from the table is.......$m.$
One end of a rod of length $L$ is fixed to a point on the circumference of a wheel of radius $R$. The other end is sliding freely along a straight channel passing through the centre of the wheel as shown in the figure below. The wheel is rotating with a constant angular velocity $\omega$ about $O$. Taking $T=\frac{2 \pi}{\omega}$, the motion of the rod is