Motion in a Straight Line - Key Vocabulary

Vocabulary flashcards from lecture notes on motion in a straight line.

1-D Motion

Motion along a straight line.

Kinetics

Study of motion of bodies.

2-D Motion

Motion in a plane; examples include circular motion and projectile motion.

3-D Motion

Motion in space.

Path

It is the way of movement of body, and length of path is called path length. It may be curved or straight.

Frame of reference

A co-ordinate system used to describe the position, velocity, and acceleration of an object.

Motion

A body is said to be in motion if it changes its position with respect to time and its surroundings.

Particle

If the size of the body is very less than the path transversed, then it's considered as a particle.

Object

If the size of the body is comparable to the path transversed then it is considered as an object.

Distance

It is the actual path length travelled by the body in motion; it is a scalar quantity and has only one value; in a round trip, it is never zero.

Displacement

It is the shortest length travelled by the body in motion or the change in position between the initial and final points; it is a vector quantity and can have infinite values; it may be zero, positive, or negative; in a round trip, it is equal to zero.

Velocity

The ratio of displacement to time interval; a vector quantity measured in m/s or km/h.

Average Velocity

The ratio of change in position (total displacement) to time interval.

Instantaneous Velocity

Velocity at a given instance of time.

Uniform Velocity

Equal displacement covered by a body in equal time intervals.

Non-Uniform Velocity

Unequal displacement covered by a body in equal time intervals.

Speed

Distance over time; a scalar quantity measured in m/s or km/h.

Acceleration

The rate of change of velocity; a vector quantity measured in m/s^2.

Average Acceleration

Total change in velocity in a given interval of time.

Instantaneous Acceleration

Acceleration of a body at a given instant of time.

Uniform Acceleration

Equal change in velocity in equal intervals of time.

Retardation

If the direction of velocity and acceleration are in opposite directions, the body is said to be decelerated or retarded.

Relative Velocity

Motion of one body with respect to another moving body.

Vectors

Quantities that have direction as well as magnitude and follow vector's law of addition.

Scalars

Quantities that only have magnitude and follow algebraic sum.

Tensors

Type of scalars with magnitude as well as direction but independent of angle

Axial Vector

Direction of this vector is along the axis of rotation and perpendicular to plane.

Polar Vector

This vector gives the position of a point with respect to another.

Equal Vectors

Vectors that have the same direction and equal magnitudes.

Unit Vector

Magnitude of this vector is unity (1).

Null Vector

Magnitude of this vector is zero; has no specific direction.

Co-linear Vectors

All vectors exist along the same line.

Co-Planer Vectors

All vectors exist in the same plane.

Co-Initial Vectors

These vectors initiate or originate from a common point.