Question

A cyclist observes a passenger in a bus. He finds that the passenger closed his glass window displacing $20cm$ in forward direction with constant speed, in $1s$. Bus overtakes the cyclist in $3s$. Initially he was at the middle of the bus as shown in the figure. Length of the bus is $18m$. Both cyclist and bus are moving with constant speed in the same direction. The velocity (in $m/s$ ) of the glass window with respect to cyclist was

Answer 1

Answer: 3.20

Let's designate $V_m,V_B$ and $V_W$ as the speeds of man, bus and window, respectively, with respect to ground.
Clearly, $9m=\left(V_B-V_m\right)\times 3...(i)$
and for bus and window:
$\frac{20}{100}=\left[V_W-V_B\right]\times 1...(ii)$
Adding (i) and (ii), we get
$V_W-V_m=3.2=V_{Wm}$