Posted by **Hannah** on Thursday, June 7, 2012 at 4:57pm.

A dentist causes the bit of a high-speed drill to accelerate from an angular speed of 1.44 x 104 rad/s to an angular speed of 5.05 x 104 rad/s. In the process, the bit turns through 1.77 x 104 rad. Assuming a constant angular acceleration, how long would it take the bit to reach its maximum speed of 8.95 x 104 rad/s, starting from rest?

Do I start by subtracting the two angular speeds?

- Physics(Please help) -
**Elena**, Thursday, June 7, 2012 at 5:29pm
ω=ωₒ+ε•t,

t= (ω-ωₒ)/ε……..(1).

Plug (1) in following

φ =ωₒ•t +ε•t²= (ω²-ω²ₒ)/2•ε .

ε= (ω²-ω²ₒ)/2• φ =(25.5-2.07) •10^8/2•1.77•10^4 =6,32•10^4 rad/s²

Now,

ω1=ωₒ+ε•t1,

t1 = (ω1-ωₒ)/ ε =(8.95-0) •10^4/ 6,32•10^4 =1.42 s.

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