Kinematics Question 359
Question: If a car at rest accelerates uniformly to a speed of 144 km/h in 20 s, it covers a distance of
Options:
A) 2880 m
B) 1440 m
C) 400 m
D) 20 m
Show Answer
Answer:
Correct Answer: C
Solution:
Initial velocity of car (u) = 0 Final velocity of car $ ( v )=144km/hr=40m/s $ Time taken = 20s We know that, $ v=u+at $
$ 40=a\times 20\Rightarrow a=2\text{ m/}{{s}^{2}}\text{.} $
$ \text{Also, }{{v}^{2}}-u^{2}=2as\Rightarrow s=\frac{{{v}^{2}}-u^{2}}{2a} $
$ \Rightarrow s=\frac{{{( 40 )}^{2}}-{{( 0 )}^{2}}}{2\times 2}=\frac{1600}{4}=400\text{ m} $
