The graph is a hoirzontal line. Velocity is zero.

The slope > 0 (positive). The object is moving towards the end position

The slope <0 (negative). The object is moving towards the start position

Speed or velocity is at middle instant of the time interval.

Constructing Speed time graph or velocity time graph

Construct from a distance-time graph (or a displacement-time graph)

Displacement and v-t graph The following slides show you the relationship between displacement (S) and the v-t graph (velocity-time graph)

Area = 0.6 x ( ) Area = speed x time = distance Graph area under the graph? area under the graph from t = 0.1s to 0.2s is the distance travelled during t=0.1s to 0.2s

V1V1 Displacement travelled by the object from time t 1 to t 2 = area A

The area under v-t graph V/ms -1 t/s v2v2 v1v1 t2t2 t1t1 Displacement due to v 1 from t 1 to t 2 Displacement due to the increase of velocity from v 1 to v 2 from t 1 to t 2

c is the y-intercept, c = 0. Slope m= a. The equation isv =at y = mx

‘at’ or ‘v’ t S = area

ymxc

u ut at t 1/2 (a t 2 ) u v t S=(u+v)t/2

no s v a t

u,v,a& scan be ‘+’ or ‘-’ depend on direction

v = - 4ms -1 Case 1 u = 1ms -1 v = 4ms -1 t = 3s a = ? Case 2 ‘+’direction u = 1ms -1 t = 5s