Question

The velocity-time graph of the motion of a car is shown in the figure. The displacement travelled by the car in 9 s is

• A. 5 m
• B. 12 m
• C. Zero
• D. 45 m

Answer 1

The correct option is A 5 m

Displacement = Area under v-t graph

In the given graph, displacement of the car in 9 seconds, s = Area ΔABO + Area ΔABC + Area ΔCDF
$\Rightarrow s=(\frac{1}{2}\times OB\times AB)+(\frac{1}{2}\times BC\times AB)+(\frac{1}{2}\times CD\times DF)$
$\Rightarrow s=(\frac{1}{2}\times 2\times 10)+(\frac{1}{2}\times 3\times 10)+(\frac{1}{2}\times 4\times (-10\left)\right)$
$\Rightarrow s=10+15-20$
$\Rightarrow s=5m$
Hence, the correct answer is option (a).