Rotational Motion of a wheel turning

[Falinox]

Homework Statement

A wheel starting from rest accelerates at 1.2 rad/s² counterclockwise.
A) How long does it take to turn through 60 revolutions?
B)What is the rotational speed at that time?

2. The attempt at a solution

I converted 1.2rad/s² to 1.885 rev/s² by dividing by 2πrad (2 pi radians).
So where can I go from here?

Once I find the time in part A I can use the fact that ω=Δθ/ΔT to find the "rotational speed" correct?

 

[tiny-tim]

Welcome to PF!

Hi Falinox! Welcome to PF!

I converted 1.2rad/s² to 1.885 rev/s² by dividing by 2πrad (2 pi radians).
So where can I go from here?

Once I find the time in part A I can use the fact that ω=Δθ/ΔT to find the "rotational speed" correct?

(btw, always leave a space between the number and the unit)

No, you need to use the standard constant acceleration equations, using angular displacement speed and acceleration instead of the linear versions.

 

[eczeno]

and i suggest you use radians rather than revolutions; the equations look much nicer that way.

 

[Falinox]

Hi Falinox! Welcome to PF! (btw, always leave a space between the number and the unit)

No, you need to use the standard constant acceleration equations, using angular displacement speed and acceleration instead of the linear versions.

Thanks for the reply!

ω²=ω₀²+2αθ
Given: ω₀=0 rad/s, α=1.2 rad/s²

Is θ my 60 rev? (maybe convert 60 rev to rad?)

 

[eczeno]

that is the right idea, and yes, theta=60rev, but make sure your units all match before plugging things in. your formula is only true if you use radians, so i would recommend that.