Question

An object $A$ is moving with $10m/s$ and $B$ is moving with $5m/s$ in the same direction as shown. Initially $A$ is $100m$ behind $B$ as shown. Find the time taken by $A$ to meet $B$

• A. $18s$
• B. $16s$
• C. $20s$
• D. $17s$

Answer 1

The correct option is C $20s$

Let us solve the problem in a frame relative to object $B$.
So, we have velocity of object $A$ w.r.t to object $B$ as
$V_{AB}=V_A-V_B=10-5=5m/s$
And, distance between the two objects is $100m$

$\therefore$ time taken by $A$ to meet $B$ is given by
$t=\frac{100}{V_{AB}}=\frac{100}{5}=20sec$