KEAM 2019 Physics and Chemistry Paper

In figure, speed of boat v0=4km∕h, speed of river vr=3km∕h and width of river =2km.The magnitude of the resultant velocity is
v‌res ‌=√vb2+v12=√32+42
⇒‌‌v‌res. ‌=5km∕h
Since, horizontal component (speed of boat) remain constant, so time taken in travelling 2km distance is
t=‌

2

4

=0.5h
In 0.5h, distance travelled by object with resultant velocity
D=v‌res ‌×t=5×0.5=2.5km