Keep it the Same (Part 2)

When we first learn physics, we focus on linear motion—objects moving in a straight line. Now that we are adding rotational motion, the best approach is not to overcomplicate things. Instead, relate everything back to what you already know.

The key is simple: rotational motion uses the same ideas as linear motion—just with a twist (literally).

Here’s the side-by-side comparison chart I use:

Linear Motion	Rotation Motion
d = vit + ½ at^2	Θ = ωit + ½ αt^2
vf = vi + at	ωf = ωi + αt
vf^2 = vi^2 + 2ad	ωf^2 = ωi^2 + 2αΘ
F = ma	F = mα
p = mv	L = Iω
Ke = ½ mv^2	Ke = ½ Iω^2

Notice how every linear formula you learned earlier has a direct rotational version! The quantities match up, just like we discussed last week:

• Force (F) becomes Torque (𝝉)

• Mass (m) becomes Moment of Inertia (I)

• Velocity (v) becomes Angular Velocity (⍵)

• Acceleration (a) becomes Angular Acceleration (𝛂)

• Distance (d) becomes Angular Displacement (𝚹)

  
  

If you focus on matching the parts, rotational problems will feel just like linear problems.

Need Help with AP Physics? Physics builds step-by-step. If you’re feeling stuck or want extra practice before your next quiz, I’m here to help you build momentum and confidence!

📧 Contact me at Kevin@doyletutor.com to schedule a tutoring session and keep moving forward!