Physics - Kinematics Question with Solution | TestHub
Figure shows a river flowing towards right, there is a bridge over river perpendicular to flow. A boat starts perpendicular to flow with velocity Column II shows required relative velocity and column I gives the possible directions.
Column I | Column II |
|---|---|
(A)
| (P) Direction of velocity of boat relative to a person moving on bridge in y > 0 direction. |
(B)
| (Q) Direction of flutter of flag relative to an observer on boat if wind is flowing towards y < 0 direction. |
(C)
| (R) Direction of velocity of boat as seen by a cyclist moving on river bank along x > 0 direction. |
(D)
| (S) Direction of velocity of man on bridge relative to person on boat |
| (T) Direction of velocity of cyclist relative to person on boat |
Options:
Answer:
Solution:
Boat's ground velocity is u along +x plus v_B/W along +y. Relative to a person on the bridge moving along +y, the x-component u remains: purely +x when the y-components match, so arrow A matches P. Flag flutter relative to boat with wind along -y: relative wind has components (-u, downward), arrow B; B also fits S and T (velocity of man on bridge relative to boat, and cyclist relative to boat, both have -y components). Arrow C (up-left) fits R and S: boat seen by a cyclist moving faster along +x has relative velocity (-x, +y). Arrow D (down-right) fits P and T. Hence A->P, B->QST, C->RS, D->PT.
