Question

Two cars get closer by 9 m every second while travelling in the opposite directions. They get closer by 1 m every second while travelling in the same directions. What are the speeds of the cars?

• A. $5m{s}^{-1}$ and $4m{s}^{-1}$
• B. $4m{s}^{-1}$ and $3m{s}^{-1}$
• C. $6m{s}^{-1}$ and $3m{s}^{-1}$
• D. $6m{s}^{-1}$ and $5m{s}^{-1}$

Answer 1

Answer: (A)

$5m{s}^{-1}$ and $4m{s}^{-1}$

Let speeds of the cars be $x$ & $y$ m/s
For the cars travelling in opposite direction: $x+y=9$
For the cars travelling in same direction: $x-y=1$
Thus, solving the equations, $x=5$ m/s and $y=4$ m/s