6.3 SPM Practice (Long Questions)

Question 12 (5 marks):
Diagram 7 shows a distance-time graph for the journey of a car from Kuala Lumpur to Ipoh.


(a) State the duration of time, in minutes, the driver stopped and rest at Tapah.
(b) Calculate the speed, in kmh^-1, of the car from Kuala Lumpur to Tapah.
(c) Calculate the average speed, in kmh^-1, of the car for whole journey.


Solution:
(a)
1400 – 1345 = 15 minutes
The driver stopped and rest at Tapah for 15 minutes.


(b)
$\begin{array}{l}\text{Speed}=\frac{\text{Distance}}{\text{Time}}\\ \text{Speed}=\frac{152\text{ km}}{1\frac{3}{4}\text{ h}}\leftarrow \boxed{\begin{array}{l}1345-1200\\ =1\text{ h }45\mathrm{mins}\end{array}}\\ \text{Speed}=86.86{\text{ kmh}}^{-1}\\ \\ \text{Speed of the car from Kuala Lumpur}\\ \text{to Tapah}=86.86{\text{ kmh}}^{-1}\end{array}$


(c)
$\begin{array}{l}\text{Average speed}=\frac{\text{Total distance}}{\text{Time taken}}\\ =\frac{205\text{ km}}{3\frac{1}{3}\text{ h}}\leftarrow \boxed{\begin{array}{l}1520-1200\\ =3\text{ h 20 mins}\end{array}}\\ \text{Average speed}=61.5{\text{ kmh}}^{-1}\\ \\ \text{Average speed of the car for the}\\ \text{whole journey}=61.5{\text{ kmh}}^{-1}\end{array}$