MOTION IN A STRAIGHT LINE
An object is said to be in continuously changing relative to a reference point such as an observer or a detection device. For example, when we walk or run our position is continuously changing with respect to the ground.
Hence:
LINEAR MOTION
➢ This is the motion or movement of an object in a straight line.
DISTANCE AND DISPLACEMENT
To define the position of an object we first choose a frame reference.
FRAME REFERENCE
➢ This set of axes from which an observer can measure the position and motion of points in a system.
1. DISTANCE (d)
➢ This is the length between two points taken by a body while in motion.
• The SI – Unit of distance is meter (m)
• Other units of distance are cm, mm and km.
o Distance is a scalar quantity since it has magnitude without direction.
2. DISPLACEMENT (S)
➢ This is the distance covered in a particular direction.
• The SI – Unit of displacement is meter (m)
• Other units of displacement are cm, mm and km.
o Displacement is a vector quantity since it has both magnitude and direction.
NOTE:
Both distance and displacement has the same SI – Unit.
Example
Glory runs round a circular track of length 500m
(a) What distance does she cover?
(b) What is her displacement from the starting point?
Solution
(a) Distance is actual ground covered.
Distance = Length of track x 2
Distance = 500m x 2
Distance = 1000m
(b) Displacement means how far she is from the starting point.
Since she ends the race at the starting point, the displacement is zero (o).
FULL NOTES
