# Motion

## 01 Motion

• Motion is a change of position.
• A body is said to be in motion (or moving) when its position changes continuously with respect to a stationary object taken as reference point.

#### SCALAR AND VECTOR QUANTITIES

Scalar quantities

• The physical quantities which require only magnitude and not direction for their complete description are called ‘scalar quantities’.
• Example: Distance, speed, time, area

Vector quantities

• The physical quantities which need both magnitude and direction for their complete description are called ‘vector quantities’.
• Example: Displacement, velocity, force

#### DISTANCE

Discovery of Cell:

It is the length of actual path traversed by a body between its initial and final positions, irrespective of the direction in which the body travels.

#### DISPLACEMENT

• Displacement refers to the straight line path between the initial and the final positions.
• Its SI unit is in metres (m).

COMPARISON BETWEEN DISTANCE AND DISPLACEMENT

 DISTANCE DISPLACEMENT The distance travelled refers to the actual length of the indirect path. Displacement refers to the straight line path between the initial and the final positions. Distance is a scalar quantity. Displacement is a vector quantity. The distance travelled by a moving body cannot be zero The final displacement of a moving body can be zero. Direction doesn’t matter Direction matters