1.The length of the seconds hands of a clock is 1cm.The change in velocity in its tip is what?2.A body starts moving with velocity u=10m/s.It experiences a retardation equal to 0.2v2 .Its velocity after 2s is what?

Dear Chandan das

given retardation = 0.2v²

or  -dv/dt =0.2v²

     -dv/v²=0.2 dt

 intigrate

1/V = 0.2t +c

now use initial condition  at t= o ,v=10 m/sec

so    c= 0.1

equation become 

 1/V = 0.2t +0.1

so at t=2 sec

1/v = 0.4+0.1

v= 2 m/sec

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