Question

A dog weighing 5 kg is standing on a flat boat
so that it is 10 metre from the shore. If the dog
walks 4 metre on the boat towards shore and
then halts. The boat weighs 20 kg and one can
assume that there is no friction between it and
the water. How far is the dog from the shore at
the end of this time?
1. 3.2 m 2. 0.8 m 3. 10 in 4. 6.8 m​

Answer 1

Answer:

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Explanation:

hibvbn

bye

Answer 2

Answer:

The correct answer is B.

GIven,

Mass of dog is 5kg,

Mass of the boat is 20kg

x

1

is the distance of the center of mass of boat from the shore, and x

c

is the distance of the center of mass of the system from the shore.

X

cm

=

20+5

5×10+20×1

=2+

5

4

×1

Now, let boat move x distance away from the shore when a dog moves 4m towards the shore

.

So, the distance of boat from shore=x

1

+x

Now, the distance of dog from shore =10−4+x

=6+x

Now,

x

cm

=

20+5

5×(6+x)+20×(x

1

+x)

=

25

30+25x+20x

1

equating both x

cm

5

6

+x

1

+

5

4

=2+

5

4

so,

distance=6+

5

4

=

5

34

m

=6.8m