Motion in a Straight Line

A frame of reference is

A frame of reference is an arbitrary reference system with respect to which position and time coordinates are assigned. Motion can be described only a

An inertial reference frame is one

An inertial reference frame is one in which Newton's first law correctly describes the motion of a body with no net external force. It is at rest or m

A point mass or point object

A point mass or point object is an object whose change in position is very large compared with its own size. A person on a platform for a passing trai

Distance is the length of

Distance is the length of the actual path covered and is a scalar quantity. Displacement is the difference between final and initial positions and is

Speed is distance travelled per unit

Speed is distance travelled per unit time and can never be negative. Velocity is displacement per unit time and can be positive or negative.