Question

The turntable of a record player has an angular velocity of 8.0 rad/s when it is turned off. The turntable comes to rest 2.5 s after being turned off. Through how many radians does the turntable rotate after being turned off? Assume constant angular acceleration

Answer 1

Answer:

Distance covered will be 10 radian

Explanation:

We have given initial angular velocity $\omega _i=8rad/sec$

As the record player finally stops so final angular velocity $\omega _f=0rad/sec$

Time t = 2.5 sec

From first equation of motion we know that

$\omega _f=\omega _i+\alpha t$

So $0=8+\alpha \times 2.5$

$\alpha =-3.2rad/sec^2$

Now we know that

$\Theta =\omega _it+\frac{1}{2}\alpha t^2=0\times 2.5+\frac{1}{2}\times 3.2\2.5^2=10rad$

So distance covered will be 10 radian