Question

River is flowing with velocity (3i+2j)m/s. A boat
is moving in river with velocity (3i-2j) m/s with respect to
the river. The speed of boat w.r.t ground is
(1) 1 m/s
(2) 4 m/s
(3) 6 m/s
(4) 8 m/s

please answer this question. ..its urgent (step by step answer please )​

Answer 1

Answer:

4

Explanation:

I am not sure

relative velocity of boat with river=Vbr

3i-2j-(3i+2j)

so -3i get cancelled

=-4j

taking modulus root of (-4^2)=root 16

which is=4

Answer 2

The speed of the boat with respect to the ground is equal to 6 m/s.

Given:

The velocity of the river with respect to the ground $(V_{RG})$ = (3i + 2j) m/s

The velocity of the boat with respect to the river $(V_{BR} )$ = (3i - 2j) m/s

To Find:

The magnitude of the speed of boat with respect to the ground.

Solution:

→ Let the velocity of the boat with respect to the ground be $V_{BG}$

→ If the velocity of an object A with respect to the ground is $V_{AG}$ and the velocity of an object B with respect to the ground is $V_{BG}$, then the relative velocity of B with respect to A is given by:

             $\therefore Velocity\:of\:B\:with\:respect\:to\:A\:(V_{BA} ) = V_{BG} -V_{AG}$

→ The velocity of the boat with respect to the river that is $V_{BR}$ would be given by:

      $\therefore Velocity\:of\:Boat\:with\:respect\:to\:River\:(V_{BR} ) = V_{BG} -V_{RG}$

                                    $\therefore V_{BR} = V_{BG} -V_{RG}\\\\\therefore V_{BG} =V_{BR} +V_{RG}\\\\\:{\boldsymbol{\therefore V_{BG} =[(3)\hat{\textbf{\i}}}} -(2)\hat{\textbf{\j}}}}]\: + \:[(3)\hat{\textbf{\i}}}} +\:{\boldsymbol{(2)\hat{\textbf{\j}}}}]\\\\{\boldsymbol{\therefore V_{BG}=(6)\hat{\textbf{\i}}}$

Therefore it can be said that the speed of the boat with respect to the ground is equal to 6 m/s.

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