Gradient and Area Under A GraphSPEED – TIME GRAPH

SPEED – TIME GRAPH

• SPEED INCREASE

• ACCELERATION

• UNIFORM SPEED• ACCELERATION = 0

• SPEED DECREASE• DECELERATION

The gradient under the speed –time graph also known as:(a)Rate of change of speed(b)Acceleration/deceleration

The area under the speed –time graph represents the distance travelled.

takentime

speedinitialspeedfinal )(axis-x

axis-y Gradient

b arectangle a of area

(distance)graph under theArea

Speed (ms-1 )

time (s )a

b

0

b a2

1 triangleangled-right a of area

(distance)graph under theArea

Speed (ms-1 )

time (s )a

b

0

cba

)(2

1 trapeziuma of area

(distance)graph under theAreaSpeed (ms-1 )

time (s )c

b

0

B trapeziumof area

A rectangle of area(distance)graph under theArea

Speed (ms-1 )

time (s )0

a

SPM 2014 Salleh drives his car for 150km from Butterworth to Ipoh to

visit his father. Table 6 shows the note of his journey.

Time 24 August/Saturday8.00 am Start journey9.04 am Breakfast at R&R Bukit Merah after drive for 70km9.30 am Continue journey for another 80km10.15 am Arrive at father’s house(a) Diagram 6 shows distance –time graph

(i) State the value of m and n.

(ii) Complete the graph that represent Salleh’s whole journey.

(b) Calculate the average speed, in kmh -1 for the whole journey.

Distance (km)

m=….

150

640 n=…. 135Time (min)

Diagram 6

(a) m = 150-70 =80km(b) n = 64+26 =90 min