AP Physics 1: Algebra-Based Flashcards: Rotational Kinetic Energy
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
How is the total kinetic energy of a rigid system determined?
The total kinetic energy is the sum of its rotational kinetic energy (due to rotation about its center of mass) and its translational kinetic energy (due to the linear motion of its center of mass).
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How is the total kinetic energy of a rigid system determined?
The total kinetic energy is the sum of its rotational kinetic energy (due to rotation about its center of mass) and its translational kinetic energy (due to the linear motion of its center of mass).
What is the formula for the rotational kinetic energy of a rigid system?
The rotational kinetic energy is given by the equation $K_{rot} = \frac{1}{2}I\omega^2$, where I is the rotational inertia and ω is the angular velocity.
A ball is rolling across a floor without slipping. Why is its total kinetic energy greater than just $\frac{1}{2}mv_{cm}^2$?
Its total kinetic energy is greater because it is the sum of its translational kinetic energy ($\frac{1}{2}mv_{cm}^2$) and its rotational kinetic energy ($\frac{1}{2}I\omega^2$).
If a rigid body's angular velocity is doubled while its rotational inertia remains constant, by what factor does its rotational kinetic energy change?
The rotational kinetic energy increases by a factor of four, because it is proportional to the square of the angular velocity (ω²).
What is the relationship between rotational kinetic energy, rotational inertia, and angular velocity?
The rotational kinetic energy of a rigid system is directly proportional to both its rotational inertia and the square of its angular velocity.
How does rotational kinetic energy relate to the motion of individual points within a rigid system?
Rotational kinetic energy exists because the individual points within a rotating rigid system have linear speed, and therefore kinetic energy, even if the system's center of mass is stationary.
Describe the components of total kinetic energy for a rolling object.
The total kinetic energy of a rolling object is composed of its translational kinetic energy from the motion of its center of mass and its rotational kinetic energy from its rotation.
What two variables determine the rotational kinetic energy of a rigid system?
The rotational kinetic energy of a rigid system is determined by its rotational inertia (I) and its angular velocity (ω).
Can a rigid system have rotational kinetic energy if its center of mass is at rest? Explain.
Yes, a system can have rotational kinetic energy while its center of mass is at rest because the individual points within the system are still moving and thus have kinetic energy.
A flywheel is spinning in place, fixed to an axle. What form(s) of kinetic energy does it possess?
The flywheel has rotational kinetic energy because it is rotating, but its translational kinetic energy is zero because its center of mass is at rest.