Question

Set the drifts suffered by boat in decreasing order.
(a) $d = 1000m,{v_r} = 2m{s^{ - 1}},{v_b} = 4m{s^{ - 1}}$
(b) $d = 500m,{v_r} = 1m{s^{ - 1}},{v_b} = 6m{s^{ - 1}}$
(c) $d = 1000m,{v_r} = 6m{s^{ - 1}},{v_b} = 6m{s^{ - 1}}$
[Here d is width of river, ${v_r}$ is velocity of water in river, ${v_b}$ is velocity of boat in still water]

Answer 1

Hint: In this question we have to arrange drifts suffered by boats in decreasing order.
For this, first we will find drifts for these boats and then compare them and arrange them in decreasing order.

Complete step by step solution:
We will use following formula to find drift,
${\text{Drift = }}\dfrac{{{\text{distance}}}}{{{\text{boat speed}}}}{{ \times \text{river speed}}}$
Given,
a) $d = 1000m,{v_r} = 2m{s^{ - 1}},{v_b} = 4m{s^{ - 1}}$
$\Rightarrow {\text{Drift = }}\dfrac{{{\text{1000}}}}{{\text{4}}}{{ \times 2}}$
$\Rightarrow {\text{Drift = 500}}$

b) $d = 500m,{v_r} = 1m{s^{ - 1}},{v_b} = 6m{s^{ - 1}}$
$\Rightarrow {\text{Drift = }}\dfrac{{{\text{500}}}}{6}{{ \times 1}}$
$\Rightarrow {\text{Drift = }}\dfrac{{{\text{500}}}}{6}$

c) $d = 1000m, {v_r} = 6m{s^{ - 1}},{v_b} = 6m{s^{ - 1}}$
$\Rightarrow {\text{Drift = }}\dfrac{{{\text{1000}}}}{6}{{ \times 6}}$
$\Rightarrow {\text{Drift = 1000}}$

From above calculation we can see that the decreasing order of drift suffered by boats is c, a, b.

Note: In this question we have seen that the boat is drifting. Drift is the slow moment of any object towards something. Whenever there is drift in something, that object will move from its place so there will be a velocity due to movement of the object. This velocity is called drift velocity. In this question the drift is attained by a boat.