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Question: Answered & Verified by Expert
A toy car of mass $100 \mathrm{~g}$ is moving with velocity of $(\hat{i}+2 \hat{j}-3 \hat{k}) m$, then the kinetic energy of the car is
PhysicsWork Power EnergyAP EAMCETAP EAMCET 2023 (18 May Shift 1)
Options:
  • A $7 \mathrm{~J}$
  • B $70 \mathrm{~J}$
  • C $0.7 \mathrm{~J}$
  • D $0.07 \mathrm{~J}$
Solution:
1410 Upvotes Verified Answer
The correct answer is: $0.7 \mathrm{~J}$
Mars, $m=100 \mathrm{~g}=0.1 \mathrm{~kg}$
velocity, $\vec{v}=\hat{i}+2 \hat{j}-3 \hat{k}$
Magnitude of velocity,
$|v|=\sqrt{(\hat{i})^2+(2 \hat{j})^2+(-3 \hat{k})^2}=\sqrt{14}$
Kinetic energy is given as,
$\mathrm{K}=\frac{1}{2} \mathrm{mv}^2=\frac{1}{2} \times 0.1 \times(\sqrt{14})^2=0.7 \mathrm{~J}$

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