Dynamics

What is a reference frame?

Definition: The coordinate system used in three-dimensional space to describe the motion of an object, and with respect to which the object's motion is analyzed, is referred to as an reference frame.

What is an inertial reference frame?

A reference frame in which Newton's laws of motion hold true is called an inertial reference frame.

Terminal velocity is the maximum speed that an object freely falling through a fluid eventually reaches. It happens because the force of gravity pulling it downward is balanced by the fluid resistance pushing upward. Upon reaching terminal velocity, the object stops accelerating and falls at a constant speed.

• Initially speed of the falling object increases due to the force of gravity.
• As the falling objects speed increases, it collides with more and more fluid molecules. These collisons create a resistance that works against the force of gravity.
• At a point, the upward fluid resistance becomes equal to the downward gravitational force. As a result the object stops accelerating and continues to fall at a steady speed.