Question

A 714-N man stands in the middle of a frozen pond of radius 9.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 1.2-kg physics textbook horizontally toward the north shore at a speed of 9.0 m/s. How long does it take him to reach the south shore

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Answer 1

Given, Weight of the man ( W ) = 714 N

Radius of the pond ( R ) = 9.0 m

Mass of the book ( m ) = 1.2 kg

Speed at which the book thrown ( v ) = 9.0 m/s in north direction,

Acceleration due to gravity ( g ) = 10

Let the mass of the mas = M kg

the speed of the man after throwing the book = u m/s

Initially the man is standing with his book. So, mass of the man will be

Hence, initial total mass will be ( M+m ) kg.

Therefore,

  

There is no external force acting system ( man and book ) in the direction of throw. So, there will conservation of

momentum in the direction of throw.

As, the speed of book and speed of man will be in opposite direction.

Using the conservation of momentum,

  

So, speed of the man

Distance to be travelled by the man = radius of the pond

So, time taken by man to reach the shore ( T ) =