Question

A man weighing 80 kg is standing at the centre of a flat boat and he is 20 m away from the shore. He walks 8 m on the boat towards the shore and then comes to a halt. The boat weighs 200 kg. How far is he from the shore at the end of this time?

• A. 11.2 m
• B. 13.8 m
• C. 14.3 m
• D. 15.4 m

Answer 1

The correct option is C 14.3 m

Centre of mass will not move in horizontal direction. Let x be the displacement of boat.
$80(8-x)=200x$
$640-80x=200x$
$x=2.3m$
Now, required distance from the shore,
$20-(8-x)=20-(8-2.3)$
$=20-5.7=14.3m$