Question

An empty office chair is at rest on a floor. Consider the following forces: 1. A downward force of gravity. 2. An upward force exerted by the floor. 3. A net downward force exerted by the air. Which of the forces is (are) acting on the office chair?

Answer 1

The forces acting on an office chair at rest include the downward force of gravity and the upward normal force exerted by the floor. When at rest, these forces are balanced, and any net downward force exerted by the air is negligible.

Step-by-step explanation:

On an office chair at rest, several forces can be acting simultaneously. Every object with mass experiences a downward force of gravity. This force is also known as the weight of the chair and acts towards the center of the Earth. To counteract this, there is an upward normal force exerted by the floor, which supports the chair and prevents it from accelerating downwards. These two forces are often equal in magnitude and opposite in direction when the chair is at rest, creating a state of equilibrium.

In addition to these forces, there is a net downward force exerted by the air, commonly referred to as air resistance. However, when the chair is at rest, this force is negligible because air resistance primarily acts on objects in motion. Moreover, this force is not typically present in any significant amount when considering stationary objects in air at normal conditions.

Therefore, the forces acting on the office chair are the downward force of gravity and the upward force exerted by the floor. These forces are in balance, which is why the chair doesn't move.

Answer 2

Step-by-step explanation:

When a chair is at rest on the floor , the earth will exert a force of gravity on it which is also known as its weight. This force acts on the chair in downward direction towards the centre of the earth.

The chair also experiences another force called reaction force which is exerted by the floor on which it rest . This force acts on the chair in upward direction. This force is equal to the weight of the chair in case chair is at rest or it is moving in uniform motion.

Due to these two equal and opposite forces, acting on the chair, it remains at rest, as net force becomes zero.

A net downward force exerted by air , which is the reaction force of buoyant force acting on chair in upward direction acts on the floor on which chair rests . This force does not act on the chair.

Hence out of three forces given , only two forces act on the chair.