Question

Find angular velocity which the disk needs to spin to slide box off given coefficient of friction and radius. Also need to find revolutions per second is this. please explain

Answer 1

hat you should know is

In short you must know the relation between revolution and angle.

Every one know that 1 revolution = 360 degree or = 2π radian.

(Note that this is not unit conversion but it is by definition of degree or radian)

revolutions = 2π*radian.

Dividing by time on both sides you get
Revolutions/ time = angle/ time

revolutions/ minute = 2π* radian./ minute

you can convert this into revolutions per second by dividing both sides by 60.

Revolution per second, is otherwise called frequency is denoted by the letter N and the unit is Hz.
Angle per second is other wise called angular speed ( or velocity ) is dented be the symbol ω

The relation between ω and N is ω = 2π N

In the problem you are given N and one has to calculate ω
There is no just conversion of units . It is a relation between ω and N