Everything Science Grade 10

21.7 CHAPTER 21. MOTION IN ONE DIMENSION

• Acceleration (~a) is the change in velocity (∆~v) over a time interval (∆t):

~a=∆∆~vt

• The gradient of a position - time graph (xvs.t) gives the velocity.


• The gradient of a velocity - time graph (vvs.t) gives the acceleration.


• The area under a velocity - time graph (vvs.t) gives the displacement.


• The area under an acceleration - time graph (avs.t) gives the velocity.


• The graphs of motion are summarised in Figure 21.3.


• The equations of motion are used where constant acceleration takes place:

vf = vi+at

∆~x = (vi+ 2 vf)t

∆~x = vit+^12 at^2

~v^2 f = ~v^2 i+ 2a∆~x

Physical Quantities

Quantity Vector Unit name Unit symbol

Position (x) - metre m

Distance (D) - metre m

Displacement (∆~x) X metre m

Speed (vav) - metre per second m·s−^1

Average velocity (~vav) X metre per second m·s−^1

Instantaneous velocity (~v) X metre per second m·s−^1

Instantaneous speed (v) - metre per second m·s−^1

Instantaneous acceleration (~a) X metre per second per second m·s−^2

Average acceleration (~aav) X metre per second per second m·s−^2

Magnitude of acceleration (a) - metre per second per second m·s−^2

Table 21.1: Units used inmotion in one dimension

436 Physics: Mechanics