Mechanics> kinematics...

A dog of mass 5Kg is standing on a flat boat so that he is 10m from the shore.He walks 4m on the boat towards the shore and then halts. If the mass of the boat is 20Kg, find the distance of the dog from the shore when it halts________

sindhuja P , 16 Years ago

Grade 11

2 Answers

Badiuddin askIITians.ismu Expert

Dear sindhuja

let the x1 is the distance of center of mass of boat from the shore,and Xc.m is the distance of center of mass of the system from the shore

Xc.m =(5*10 +20*x1)/(20+5)

=2 +(4/5) x₁

now let boat move x distance away from the shore when dog move 4m towards the shore

so new distance of boat from shore=x1 +x

new distance of dog from shore=10-4 +x=6+x

now

Xc.m ={5*(6+x) +20*(x1+x)}/(20+5)

=(30+25x +20x₁₎/25

=6/5 +x +4/5x₁

equate both Xc.m

6/5 +x +4/5x₁ =2 +(4/5) x₁

x=2-6/5

=4/5

so distance =6+4/5

=34/5

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Last Activity: 16 Years ago

Raunaq Mehta

let the x1 is the distance of center of mass of boat from the shore,and Xc.m is the distance of center of mass of the system from the shoreXc.m =(5*10 +20*x1)/(20+5) =2 +(4/5) x1now let boat move x distance away from the shore when dog move 4m towards the shoreso new distance of boat from shore=x1 +xnew distance of dog from shore=10-4 +x=6+xnow Xc.m ={5*(6+x) +20*(x1+x)}/(20+5) =(30+25x +20x1)/25 =6/5 +x +4/5x1 equate both Xc.m6/5 +x +4/5x1 =2 +(4/5) x1 x=2-6/5 =4/5so distance =6+4/5 =34/5

Last Activity: 9 Years ago