A dentist using a dental drill brings it from rest to maximum operating speed of 391,000 rpm in 2.8 s. Assume that the drill accelerates at a constant rate during this time. (a) What is the angular acceleration of the drill in rev/s2?
rev/s2
(b) Find the number of revolutions the drill bit makes during the 2.8 s time interval.
rev

a

b

Explanation:

From the question we are told that

    The maximum  angular   speed is  

     The  time  taken is  

     The  minimum angular speed is   this is because it started from rest

Apply the first equation of motion to solve for acceleration we have that

=>    

substituting values

converting to

  We have

According to the first equation of motion the angular displacement is  mathematically represented as

substituting values

converting to revolutions  

gravitational energy

electrical energy

kinetic energy

ligh energy