How to solve this problem

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The distance 'x' moved by a body under the action of a force varies with time 't' as x=3t^2 + 4t +5, where 'x' is expressed in metre and 't' in second. If the work done by force in the first 2 seconds is 60 J, kinetic energy of the body at t=1 sec is ?

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rishabh ·2011-09-28 01:22:25

you have x as a function of time, differentiate it to get velocity as a function of time.
put t = 2 to get vel. and use the work energy theorum (noting that there is initial velocity @ t= 2)
this gives you the mass..
nw again put t= 1 to get the new velocity , K.E = 1/2*mv'²

the answer will come out to be = 25 J

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