a barameter in elevator reads 76 cm. at rest.if elevator starts going upward with an increasing speed .what will be the new reading of barometer.wil it be smalller, greater or same? why?

When an elevator is at rest, the barometer reads 76 cm of mercury. However, when the elevator begins to move upward with increasing speed, the reading on the barometer will change. To understand why, let's break down the concepts involved.

The Basics of Barometers

A barometer measures atmospheric pressure, which is the weight of the air above us. The reading of 76 cm indicates the pressure exerted by the atmosphere at that location. When the elevator is stationary, this reading reflects the ambient atmospheric pressure.

Effects of Acceleration

When the elevator accelerates upwards, it creates an additional force acting on the barometer. This force is due to the elevator's acceleration, which effectively increases the pressure exerted on the barometer. To visualize this, think of the barometer as a column of mercury. When you push down on the column (like the upward acceleration of the elevator), the mercury level rises.

Understanding the Forces at Play

• Gravitational Force: This is the force pulling the mercury down, which is constant.
• Inertial Force: When the elevator accelerates upwards, an inertial force acts on the mercury, pushing it down further.

As a result, the combined effect of gravitational force and the inertial force from the elevator's acceleration increases the pressure on the barometer. Therefore, the reading on the barometer will be greater than 76 cm when the elevator is moving upwards with increasing speed.

Conclusion on Barometer Reading

In summary, when the elevator accelerates upwards, the reading on the barometer will be greater than 76 cm. This is due to the additional pressure created by the upward acceleration, which effectively pushes the mercury higher in the tube. Understanding these principles helps clarify how forces interact in different scenarios, such as in an accelerating elevator.