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A particle which is experience a force, given by \vec{F}= 3\vec{i}-12\vec{j},undergoes a displacement of \vec{d}= 4\vec{i}. If the particle had a kinetic energy of 3J at the begning of the displacement, What is its kinetic energy at the end of the displacement?

  • Option 1)

    10 J

  • Option 2)

    9 J

  • Option 3)

    15 J

  • Option 4)

    12 J

Answers (1)

best_answer

 

Definition of work by constant force -

w = \underset{F}{\rightarrow}.\underset{S}{\rightarrow}

- wherein

The scalar product of the force vector (\underset{F}{\rightarrow}) and the displacement vector (\underset{S}{\rightarrow})

 

 

Net work done by all the forces give the change in kinetic energy -

W=\frac{1}{2}mv^{2}-\frac{1}{2}mv{_{0}}^{2}

W= k_{f}-k_{i}

- wherein

m=mass \: of\: the\: body

v_{0}= initial\: velocity

v= final\: velocity

 

 

W = F.d = 3X4 =12J

W_{net} = \Delta KE

12 = Kf -3

Kf = 15J

 

 


Option 1)

10 J

Option 2)

9 J

Option 3)

15 J

Option 4)

12 J

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