# Elementary mechanics

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A force of 2i+7jN acts on a body of mass 5kg for 10 seconds. The body was initally moving with constant velocity of i-2jm/s.Find the final velocity of the body in m/s, in vector form. (a)5i+12j(b)12i-5j(c)10i-7j(d)7i+10j

• Elementary mechanics -

Use the kinematics equation:
Vf=Vi+at
where
Vf=final velocity=i-2j (m/s)
Vi=initial velocity, yet unknown
a=acceleration=F/m (in vector form)
t=time=10 s

a=(2i+7j)/5=0.4i + 1.4j

Vf=(i-2j)+(0.4i+1.4j)(10)
=(i-2j)+(4i+14j)
=5i+12j

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