# SPM Mathematics Trial 2021 (Selangor), Paper 2 (Question 11 & 12)

Question 12:
The speed-time graph in Diagram 7 shows the motion of an object for a period of t seconds.

(a) Calculate
(i) uniform speed,
(ii) the rate of change of speed, in ms-2, of the object in the first 5 seconds.
[3 marks]

(b) Find the value of t, if the distance travelled by the object for the first 5 seconds if half the distance travelled at uniform speed. [3 marks]

Solution:
(a)(i)
Laju seragam = 10 ms-1

(a)(ii)

(b)

$\begin{array}{l}\text{For speed-time graph, distance travelled is area under the graph}\text{.}\\ \text{Given area of trapezium}=\frac{1}{2}×\text{area of rectangle}\\ \frac{1}{2}×\left(6+10\right)×5=\frac{1}{2}×\left(t-5\right)×10\\ 80=10t-50\\ 10t=130\\ t=13\end{array}$