A disk of radius 10 cm speeds up from rest. it turns 60 radians reaching an angular velocity of 15 rad/s. what was the angular acceleration? b. how long did it take the disk to reach this velocity?​

a) The angular acceleration is 1.875 radians per square second.

b) The time taken by the disk to reach the final angular speed is 8 seconds.

Explanation:

a) Let suppose that the disk accelerates uniformly, given that initial and final angular speed (, ), in radians per second, and change in angular position (), in radians, are known. The angular acceleration (), in radians per square second, are found by using this expression:

(1)

If we know that , and , then the angular acceleration of the disk is:

The angular acceleration is 1.875 radians per square second.

b) The time taken by the disk to reach the final angular velocity is determined by the following kinematic formula:

(2)

Where is the time, in seconds.

If we know that , and , then the time taken by the disk is:

The time taken by the disk to reach the final angular speed is 8 seconds.

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.

the answer is b, have negligible mass