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📚AP Physics C: Mechanics Unit 5 Vocabulary

47 essential vocabulary terms and definitions for Unit 5 – Torque and Rotational Motion

Study Unit 5
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📚Unit 5 – Torque and Rotational Motion
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📚Unit 5 – Torque and Rotational Motion

5.1 Rotation

TermDefinition
angular accelerationThe rate of change of angular velocity with respect to time, represented by the symbol α.
angular displacementThe change in angular position of a rotating object, measured in radians.
angular velocityThe rate of change of angular position with respect to time, represented by the symbol ω.
axis of rotationThe fixed line about which a rigid body or system rotates.
constant angular accelerationA condition in which angular velocity changes at a uniform rate over time, allowing the use of kinematic equations to relate angular displacement, angular velocity, and angular acceleration.
rigid systemA collection of objects or particles that maintain fixed distances from each other and rotate as a single unit.

5.2 Connecting Linear and Rotational Motion

TermDefinition
angular accelerationThe rate of change of angular velocity with respect to time, represented by the symbol α.
angular displacementThe change in angular position of a rotating object, measured in radians.
angular velocityThe rate of change of angular position with respect to time, represented by the symbol ω.
axis of rotationThe fixed line about which a rigid body or system rotates.
linear displacementThe linear distance s traveled by a point on a rotating system.
linear motionThe motion of a point along a straight or curved path, characterized by linear displacement, velocity, and acceleration.
linear velocityThe rate of change of linear displacement with respect to time, denoted by v, related to angular velocity by v = rω.
rigid systemA collection of objects or particles that maintain fixed distances from each other and rotate as a single unit.
rotational motionThe motion of a rigid body or point rotating about a fixed axis, characterized by angular displacement, velocity, and acceleration.
tangential accelerationThe rate at which an object's speed changes, directed tangent to the object's circular path.

5.3 Torque

TermDefinition
axis of rotationThe fixed line about which a rigid body or system rotates.
cross productA vector operation between two vectors that produces a third vector perpendicular to both, with magnitude AB sin θ.
force component perpendicularThe component of a force that is perpendicular to the position vector, which is the only component that contributes to torque.
force diagramA diagram that represents the forces exerted on an object or system.
free-body diagramA visual representation showing all forces exerted on an object or system, with each force drawn as a vector originating from the center of mass.
lever armThe perpendicular distance from the axis of rotation to the line of action of an applied force.
pivot pointThe chosen point about which torque on a rigid system is calculated.
position vectorA vector denoted by r⃗ that specifies the location of a point relative to the origin.
right-hand ruleA method for determining the direction of a vector resulting from a cross product by orienting the fingers of the right hand in the direction of the first vector and curling them toward the second vector.
rigid systemA collection of objects or particles that maintain fixed distances from each other and rotate as a single unit.
torqueA measure of the rotational effect of a force on a rigid body, calculated as the product of the force component perpendicular to the position vector and the distance from the axis of rotation.

5.4 Rotational Inertia

TermDefinition
axis of rotationThe fixed line about which a rigid body or system rotates.
center of massThe point in a system where the entire mass can be considered to be concentrated for the purposes of analyzing motion and forces.
mass distributionThe spatial arrangement of mass within a system relative to a reference point or axis.
parallel axis theoremA theorem that relates the rotational inertia of a rigid system about any axis to its rotational inertia about a parallel axis through its center of mass, expressed as I' = I_cm + Md².
perpendicular distanceThe shortest distance from a point or mass element to the axis of rotation, measured at a right angle to the axis.
rigid systemA collection of objects or particles that maintain fixed distances from each other and rotate as a single unit.
rotational inertiaA measure of an object's resistance to changes in its rotational motion about a given axis; depends on both the mass of the object and how that mass is distributed relative to the axis of rotation.

5.5 Rotational Equilibrium and Newton's First Law in Rotational Form

TermDefinition
angular velocityThe rate of change of angular position with respect to time, represented by the symbol ω.
force diagramA diagram that represents the forces exerted on an object or system.
free-body diagramA visual representation showing all forces exerted on an object or system, with each force drawn as a vector originating from the center of mass.
net torqueThe vector sum of all torques acting on an object or system, which causes changes in angular motion.
rigid systemA collection of objects or particles that maintain fixed distances from each other and rotate as a single unit.
rotational equilibriumA state in which a system maintains constant angular velocity because the net torque exerted on it is zero.
torqueA measure of the rotational effect of a force on a rigid body, calculated as the product of the force component perpendicular to the position vector and the distance from the axis of rotation.
translational equilibriumThe configuration of forces such that the net force exerted on a system is zero, resulting in constant velocity.

5.6 Newton's Second Law in Rotational Form

TermDefinition
angular accelerationThe rate of change of angular velocity with respect to time, represented by the symbol α.
angular velocityThe rate of change of angular position with respect to time, represented by the symbol ω.
net torqueThe vector sum of all torques acting on an object or system, which causes changes in angular motion.
rigid systemA collection of objects or particles that maintain fixed distances from each other and rotate as a single unit.
rotational inertiaA measure of an object's resistance to changes in its rotational motion about a given axis; depends on both the mass of the object and how that mass is distributed relative to the axis of rotation.