Home
Class 11
PHYSICS
A river is flowing towards with a veloci...

A river is flowing towards with a velocity of `5 m s^-1`. The boat velocity is `10 ms^-1`. The boat crosses the river by shortest path. Hence,

A

The direction of boat's velocity is `30^@` west of north.

B

The direction of boat's velocity is north - west.

C

Resultant velocity is `5 ms^-1`.

D

Resultant velocity of boat is `5 sqrt(2) m s^-1`.

Text Solution

Verified by Experts

The correct Answer is:
A
(a.,c.) For angle `theta` in west of north,
`sin theta = (5)/(10) = 0.5`, i.e., `theta = 30^@`
`V_r` = resultant velocity
=`sqrt((10^2) - (5)^2) = 5 sqrt(3) ms^-1`
So, option (a) and (c ) are correct.
.
Promotional Banner

Topper's Solved these Questions

  • KINEMATICS-2

    CENGAGE PHYSICS|Exercise Exercise Assertion - Reasoning|5 Videos

  • KINEMATICS-2

    CENGAGE PHYSICS|Exercise Exercise Comprehension|21 Videos

  • KINEMATICS-2

    CENGAGE PHYSICS|Exercise Exercise Single Correct|76 Videos

  • KINEMATICS-1

    CENGAGE PHYSICS|Exercise Integer|9 Videos

  • KINETIC THEORY OF GASES

    CENGAGE PHYSICS|Exercise Compression|2 Videos

Similar Questions

Explore conceptually related problems

A 400 m wide river is flowing from west to east at velocity 3m/s. A boat starts from one bank and it crosses the river along the shortest path. When it reaches the middle of river, wind starts blowing horizontally along north-east at a velocity sqrt(2) m/s . Due to this, the direction of rowing of boat has to be changed for the boat to move along the shortest path. If the velocity of boat in still water with no wind blowing is 5 m/s, then choose the correct option(s).

A river is flowing with a velocity of 2m/s. If the width of river in 100 m and swimmer wants to cross river is shortest time, what time (in sec) would he take if velocity of swimmer in still water is 4 m/s ?

Velocity of boat in still water is 13 m/s. If water flows ina river with a velocity of 5 m/s. What is the difference in times taken by him to cross the river in the shortest path and in the shortest time. If the width of the river is 10 m.

The velocity of a boat in still water is 10 m//s .If water flows in the river with a velocity of 6 m//s what is the difference in times taken to cross the river in the shortest path and the shortest time.The width of the river is 80 m .

Width of a river is 30 m, velocity is 4 m//s and rowing velocity is 5 m//s (a) Make the velocity diagram for crossing the river in shortest time. Then, find this shortest time, net velocity of boatman and drigt along the river. (b) Can the boatman reach a point just oppsite on the other shore? If yes then make the velocity diagram, the direction in which the should row his boat and the time taken to cross the river in this case. (c) How long will it iake hom to row 10 m up the stream and then back to his starting point?

A 400 - m wide river is flowing at a rate of 2.0 m s^-1 . A boat is sailing with a velocity of 10 m s^-1 with respect to the water, in a direction perpendicular to the river. (a) Find the time taken by the boat to reach the opposite bank. (b) How far from the point directly opposite to the starting point does the boat reach the opposite bank ? ( c) In what direction does the boat actually move ?

A motor boat is to reach at a point 30^@ upstream on the outer side of a river flowing with velocity 5 ms^(-1) . The velocity of motor boat with respect to water is 5(sqrt3) ms^(-1) . The driver should steer the boat at an angle.

At a harbour, a boat is standing and wind is blowing at a speed of sqrt(2)m//sec. due to which , the flag on the boat flutters along north - east. Now the boat enters in to river, which is flowing with a velocity of 2m//sec . Due north. The boat starts with zero velocity relative to the river and its constant acceleration relative to the river is 0.2m//sec^(2) due east. In which direction will the flag flutter at 10 seconds ?

A boat is moving towards east velocity 4 m/s w.r.t still water and river is flowing towards north with velocity 2 m/s and the wind blowing towards north with velocity 6 m/s. the direction of the flag blown over by the wind hpisted on the boat is

Knowledge Check

  • A 400 m wide river is flowing from west to east at velocity 3m/s. A boat starts from one bank and it crosses the river along the shortest path. When it reaches the middle of river, wind starts blowing horizontally along north-east at a velocity sqrt(2) m/s . Due to this, the direction of rowing of boat has to be changed for the boat to move along the shortest path. If the velocity of boat in still water with no wind blowing is 5 m/s, then choose the correct option(s).

    A
    The initial direction of rowing of boat is at an angle of` 53^(@)` with upstream direction
    B
    Time taken to reach the middle of river is 50 seconds
    C
    After the wind starts blowing, the direction of rowing of boat is `37^(@)` with upstream direction
    D
    Total time taken by the boat to cross the river along the shortest path is 100 seconds

  • The velocity of a boat in still water is 10 m//s .If water flows in the river with a velocity of 6 m//s what is the difference in times taken to cross the river in the shortest path and the shortest time.The width of the river is 80 m .

    A
    `1s`
    B
    `10s`
    C
    `sqrt3/2s`
    D
    `2s`

  • A motor boat is to reach at a point 30^@ upstream on the outer side of a river flowing with velocity 5 ms^(-1) . The velocity of motor boat with respect to water is 5(sqrt3) ms^(-1) . The driver should steer the boat at an angle.

    A
    `30^@` w.r.t. the line of destination from the starting point.
    B
    `60^@` w.r.t. normal to the bank.
    C
    `120^@` w.r.t. stream direction
    D
    None of these