MCQ
A body of mass $(5 \pm 0.5) kg$ is moving with a velocity of $(20 \pm 0.4) m / s$. Its kinetic energy will be
- ✓$(1000 \pm 140)\,J$
- B$(1000 \pm 0.14)\,J$
- C$(500 \pm 0.14)\,J$
- D$(500 \pm 140)\,J$
✓
Answer
Correct option: A.
$(1000 \pm 140)\,J$
a
$k =\frac{1}{2} mv ^2$
$k =\frac{1}{2} mv ^2$
$k =\frac{1}{2} \times 5 \times 400=5 \times 200=1000\,J$
$\frac{\Delta k }{2 k }=\frac{\Delta m }{ m }+\frac{2 \Delta v }{ v }=\frac{0.5}{5}+\frac{2 \times 0.4}{20}$
$\Delta k =1000\left(\frac{1}{10}+\frac{4}{100}\right)=1000\left(\frac{10+4}{100}\right)=140\,J$
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