Question

A computer hard disk 8.0 cm in diameter is initially at rest. A small dot is painted on the edge of the disk. The disk accelerates at 680rad/s2 for 12s, then coasts at a steady angular velocity for another 12s.What is the speed of the dot at t = 1.0 s?

Answer 1

Step-by-step explanation:

According to the kinematic equation,

`\omega_(f) = \omega_(i) + at`

And, we are given

`\omega_(i)` = 0, a = 680
`rad/s^(2)`

t = 12 sec

Putting the given values into the above formula as follows.

`\omega_(f) = \omega_(i) + at`

=
`0 + 680 * 12`

= 8160 rad/s

Also, we know that

`\\u = r * \omega`

=
`(0.08 m)/(2) * 8160 rad/s`

= 326.4 m/s

Thus, we can conclude that the speed of the dot at t = 1.0 sec is 326.4 m/s.