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A particle moves from a point \left( { - 2\hat i + 5\hat j} \right) to \left( {4\hat j + 3\hat k} \right) when a force of \left( {4\hat i + 3\hat j} \right) N is applied. How much work has been done by the force?

  • Option 1)

    8 J

  • Option 2)

    11 J

  • Option 3)

    5 J

  • Option 4)

    2 J

 

Answers (1)

best_answer

As we discussed in

Definition of work by constant force -

w = underset{F}{
ightarrow}.underset{S}{
ightarrow}

- wherein

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

 

 \vec{s}=\vec{r}_f-\vec{r}_i = 2\dot{i}-\dot{j}+\dot{3k}

w=\vec{f}.\vec{s}= (4\dot{i} +3\dot{j}).2\dot{i}-\dot{j}+\dot{3k}

w=8-5 \:=5J


Option 1)

8 J

Incorrect

Option 2)

11 J

Incorrect

Option 3)

5 J

Correct

Option 4)

2 J

Incorrect

Posted by

divya.saini

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