AP Physics 1: Algebra-Based Flashcards: Rotational Equilibrium and Newton’s First Law in Rotational Form
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 11 cards to help you master important concepts.
What is rotational equilibrium?
Rotational equilibrium is a configuration where the net torque exerted on a system is zero, represented by the equation Στ = 0.
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What is rotational equilibrium?
Rotational equilibrium is a configuration where the net torque exerted on a system is zero, represented by the equation Στ = 0.
Can a system be in translational equilibrium but not rotational equilibrium?
Yes, a system can have a constant translational velocity (translational equilibrium) while its angular velocity is changing due to a net torque.
A spinning figure skater pulls her arms in, causing her to spin faster. Is she in rotational equilibrium during this process?
No, because her angular velocity is changing, the net torque exerted on the system cannot be zero, so she is not in rotational equilibrium.
Can a system be in rotational equilibrium but not translational equilibrium?
Yes, a system can have a constant angular velocity (rotational equilibrium) while simultaneously accelerating translationally.
What is the consequence of an unbalanced net torque on a rigid system?
If the torques on a rigid system are not balanced (net torque is non-zero), the system's angular velocity must be changing.
Contrast the conditions for rotational equilibrium and translational equilibrium.
Rotational equilibrium requires zero net torque for constant angular velocity, while translational equilibrium requires zero net force for constant translational velocity; a system can be in one state without being in the other.
What is the rotational analog of Newton's first law?
The rotational analog of Newton's first law states that a system will maintain a constant angular velocity only if the net torque exerted on it is zero.
A bicycle wheel is spinning at a constant 10 rad/s. What can you conclude about the net torque on the wheel?
Since the wheel has a constant angular velocity, it is in rotational equilibrium, and therefore the net torque exerted on it must be zero.
What is the mathematical condition for rotational equilibrium?
The mathematical condition for rotational equilibrium is that the sum of all torques acting on the system equals zero: Στ = 0.
How does the rotational corollary to Newton's second law explain a change in angular velocity?
This corollary states that a change in angular velocity is caused by an unbalanced or non-zero net torque exerted on the rigid system.
Under what condition does a system's angular velocity remain constant?
A system's angular velocity remains constant when the net torque exerted on the system is zero (Στ = 0).