QJEEM19Ph9991: JEE Main 2019 Physics - Class 11 JEEM19Ph9991 Solution: The position vector of a particle changes with time according…

Question

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The position vector of a particle changes with time according to the relation

\vec{r} (t) = 15 t^{2} \hat{i} + (4 - 20 t^{2}) \hat{j}

What is the magnitude of the acceleration at t = 1 ?

Accepted Answer

\vec{r} = (15 t^{2}) \hat{i} + (4 - 20 t^{2}) \hat{j}

\vec{v} = \frac{d \vec{r}}{d t} = (30 t) \hat{i} - (40 t) \hat{j}

\vec{a} = \frac{d \vec{v}}{d t} = (30) \hat{i} - (40) \hat{j}

| \vec{a} | = 50

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