Kinematics Question 369
Question: A bike accelerates from rest at a constant rate $ 5m/s^{2} $ for some time after which it decelerates at a constant rate $ 3m/s^{2} $ to come to rest. If the total time elapsed it’s 8 second, the maximum velocity acquired by the bike it’s given by
Options:
A) 5 m/s
B) 10 m/s
C) 12 m/s
D) 15 m/s
Show Answer
Answer:
Correct Answer: D
Solution:
$ {V _{\max }}=0+5t _{1}\text{ }….\text{(i)} $
$ \text{0=}{V _{\max }}-3t _{2}\text{ }….\text{(ii)} $
$ \Rightarrow t _{1}+t _{2}=8={V _{\max }}( \frac{1}{5}+\frac{1}{3} ) $
$ \Rightarrow {{V} _{\max }}=\frac{8\times 15}{8}=15\text{ m/s} $
