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Work, Energy, Power and Collision — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsWork, Energy, Power and Collision1 Mark
MCQ
A force $\boldsymbol{F}=(5 \hat{\boldsymbol{i}}+3 \hat{\boldsymbol{j}})$ newton is applied over a particle which displaces it from its origin to the point $\boldsymbol{r}=(2 \hat{i}-1 \hat{\boldsymbol{j}})$ metres. The work done on the particle is
  • A
    $-7$ joules
  • B
    $+13$ joules
  • ✓
    $+7$ joules
  • D
    $+11$ joules
✓

Answer

Correct option: C.
$+7$ joules
$W=\vec{F} \cdot \vec{s}=(5 \hat{i}+3 \hat{j}) \cdot(2\hat{i}\hat{j})=10-3=7\mathrm{~J}$

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