Pendulum is suspended from the ceiling of a stationary elevator, and the period is measured. if the elevator moves with constant velocity, does the period (a) increase, (b) decrease, or (c) remain the same? if the elevator accelerates upward, does the period (a) increase, (b) decrease, or (c) remain the same?

option (c)

option (b)

Explanation:

The formula for the time period of simple pendulum is given by

Where, L be the effective length of the pendulum and g be the acceleration due to gravity acting on the pendulum.

(i) As the elevator moves with constant velocity, then there is no change in the value of g so the period remains same. option (c)

(ii) If the elevator accelerates upwards, the acceleration acting on the pendulum increases and then the time period of the pendulum decreases.

option (b)

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =