#textbook #physics #freefall #airresistance #terminalvelocity

Ch:- 3

Pg:- 49,50

1. Free Fall (Ignoring Air Resistance)

Free fall refers to the motion of an object when it is only influenced by the force of gravity, and no other forces (like air resistance) are acting on it. In a vacuum (where there is no air), all objects, regardless of their mass, fall with the same acceleration due to gravity. On Earth, this acceleration is approximately 9.8 m/s^2 and is denoted as g.

2. Air Resistance (Drag Force)

When an object falls through air, it experiences a resistive force called air resistance or drag. This force opposes the motion of the object and increases with the object's speed. The magnitude of air resistance depends on several factors:

• Velocity of the object: The faster the object moves, the greater the air resistance.

• Cross-sectional area: A larger area facing the direction of motion experiences more drag.

• Shape of the object: More streamlined shapes experience less air resistance.

• Density of the air: Denser air increases the resistive force.

3. Terminal Velocity

As the object falls, it initially accelerates due to gravity. However, as its velocity increases, the air resistance acting on it also increases. Eventually, the air resistance force becomes equal in magnitude to the gravitational force acting on the object. At this point, the net force on the object becomes zero, and the object no longer accelerates. This constant speed at which the object falls is called terminal velocity.

When the object reaches terminal velocity, the upward drag force equals the downward gravitational force.