1.

The angular acceleration a of a spinning top as a function of t is : alpha = 3t^(2)+ 5t. At t = 0, the angular velocity omega_(0) = 10 rad/s and angular position theta = 8 rad. The angular position as a function of time t is given by which of the following expression?

Answer»

`(1)/(4) t^(4) + (5)/(6) t^(3) + 10 t + 8`
`(5)/(6) t^(4) + (1)/(4) t^(3) + (2)/(5) t + 8`
`2t^(4) + 3t^(3) + 5t + 8`
`(1)/(4) t^(4) + (3)/(4) t^(3) + 6t^(2) + 8`

Solution :Given : `ALPHA = 3t^(2) + 5t`
`alpha = (d^(2) THETA)/(dt^(2)) = 3t^(2) + 5t "" … (i)`
`alpha = (d^(2) theta)/(dt^(2)) = 3t^(2) +5t "" …. (i)`
Integrate both sides w.r.t. t in equation (i) , we get
`(d theta)/(dt) = t^(3) + (5)/(2) t^(2) + C_(1)`
where `C_(1)` is a constant of integration .
or `omega = (d theta)/(dt) = t^(3) + (5)/(2) t^(2) + C_(1)`
Using initial conditions , at t = 0 , `omega_(0) = 10` RAD/s
`THEREFORE C_(1) = 10` rad/s
or `(d theta)/(dt) = t^(3) + (5)/(2) t^(2) + 10 "" .... (ii)`
Integrate both sides w.r.t t in equation (ii) , we get
`theta = (1)/(4) t^(4) + (5)/(6) t^(3) + 10 t + C_(2)`
where `C_(2)` is a constant of integration .
Using initial conditions , at t = 0 , `theta_(0) = 8` rad
`therefore C_(2) = 8` rad or `theta = (1)/(4) t^(4) + (5)/(6) t^(3) + 10 t + 8`


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