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A ball is spun with angular acceleration \mathrm{\alpha=6 \mathrm{t}^{2}-2 \mathrm{t}} where t is in second and \mathrm{\alpha} is in rad s-2\text { At } \mathrm{t}=0 \text {, } the ball has angular velocity of \mathrm{10 \; \mathrm{rads}^{-1}} and angular position of 4 rad. The most appropriate expression for the angular position of the ball is :

Option: 1

\mathrm{\frac{3}{2} t^{4}-t^{2}+10 t}


Option: 2

\mathrm{\frac{t^{4}}{2}-\frac{t^{3}}{3}+10 t+4}


Option: 3

\mathrm{\frac{2 t^{4}}{3}-\frac{t^{3}}{6}+10 t+12}


Option: 4

\mathrm{2 t^{4}-\frac{t^{3}}{2}+5 t+4}


Answers (1)

best_answer

\mathrm{\alpha=6 t^{2}-2 t }

\mathrm{\frac{d \omega}{d t}=6 t^{2}-2 t }

\mathrm{\int_{10}^{\omega} d \omega=\int_{t=0}^{t}\left(6 t^{2}-2 t\right) d t \\ }

\mathrm{\omega-10=\left [\frac{6t^{3}}{3}\frac{-2t^{2}}{2} \right ]_{0}^{t} }

\mathrm{\omega=10+2 t^{3}-t^{2} }        --------(1)

\mathrm{\frac{d\theta }{dt}=10+2t^{3}-t^{2}}

\mathrm{\int_{\theta=4}^{\theta} d \theta=\int_{t=0}^{t}\left(10+2 t^{3}-t^{2}\right) d t }


\mathrm{\theta-4=\left[10 t+\frac{2 t^{4}}{4}-\frac{t^{3}}{3}\right]_{0}^{t} \\ }


\mathrm{\theta=\frac{t^{4}}{2}-\frac{t^{3}}{3}+10 t+4 }

Hence 2 is correct answer.
 

Posted by

himanshu.meshram

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