Question

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 $2/\pi$ Hz. Which of the following statements is correct?

• A. The spring balance reads the weight of man as 60kg
• B. The spring balance reading fluctuates between 60 kg. and 70 kg
• C. The spring balance reading fluctuates between 50 kg and 60 kg
• D. The spring balance reading fluctuates between 50 kg and 70 kg

Answer 1

The correct option is A The spring balance reads the weight of man as 60kg

Here,

The option $A$ is the correct answer because

as you know spring balance observe normal reaction between contacting surface. it is effected only when lift accelerated or decelerated .

if lift is moving upward with acceleration $a$

then, observation of spring balance will be $=m(g+a)$ , where m is mass of man

when lift is moving downward with acceleration a then, observation of spring balance will be $=m(g-a).$

but when lift is moving upward or donward with constant velocity then, observation will be remain same.

hence, observation of man's weight is $60kg$ on spring balance.