Rotational Kinematics


Click for the questions that go with this reading

Mathematically, the translational kinematics that was studied before behaves the same as rotational kinematics.

Translational kinematics Rotational kinematics
The velocity, v, changes the position ,x. The angular velocity, ω,changes the angle, θ.
The acceleration, a, changes the velocity, v The angular acceleration, α, changes the velocity, ω.


Example 4
  • Question
  • Solution on Paper
  • Video Solution

In the early 1900's, planes had to be started by hand. Many planes can still be started like this today, it is called "hand propping." This process means that a pilot was inside the plane while another person spun the propeller by hand to start the engine. Once the engine started, they quickly moved clear of the spinning propeller. Below is a 48 second video showing what it looks like to hand prop at 1941 PT-22 trainer.

This video can be found at



During a hand prop starting procedure, when the propeller is at 0.383 radians it is moving at 1.1 radians/sec. At 2.51 radians it is moving at 4.67 radians/sec in the same angular direction. What is the angular acceleration of the propeller?


This is what your paper should look like. Notice the list of givens, the picture, the description above each equation, and the units and numbers. It takes up a lot of space.

This is what you paper should look like

This video can be found on YouTube at




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by Tony Wayne ...(If you are a teacher, please feel free to use these resources in your teaching.)