AP Physics C: Mechanics Flashcards: Resistive Forces
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.
What is the mathematical equation for a resistive force that is linearly dependent on velocity?
The equation for a resistive force is $\vec{F}_{r}=-k\vec{v}$, where k is a constant and $\vec{v}$ is the object's velocity.
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What is the mathematical equation for a resistive force that is linearly dependent on velocity?
The equation for a resistive force is $\vec{F}_{r}=-k\vec{v}$, where k is a constant and $\vec{v}$ is the object's velocity.
What is the result of applying Newton's second law to an object experiencing a resistive force?
Applying Newton's second law to an object upon which a resistive force is exerted results in a differential equation for the object's velocity.
Describe the general motion of an object falling from rest that is subject to both gravity and a resistive force.
The object accelerates from rest, and as its velocity increases, the opposing resistive force also increases, causing the acceleration to decrease until it reaches zero at terminal velocity.
What is a resistive force?
A resistive force is a velocity-dependent force that acts in the opposite direction of an object's velocity.
In the equation $\vec{F}_{r}=-k\vec{v}$, what does the negative sign indicate?
The negative sign indicates that the resistive force vector is always in the direction opposite to the object's velocity vector.
When does a falling object reach terminal velocity?
An object reaches terminal velocity when the upward resistive force grows to become equal in magnitude to the constant downward force of gravity, causing the net force and acceleration to become zero.
What is terminal velocity?
Terminal velocity is the maximum speed an object achieves when a constant force (like gravity) and an opposing resistive force become equal in magnitude, resulting in zero net force.
A skydiver jumps from a plane. How does the resistive force of the air change as their speed increases?
As the skydiver's speed increases, the magnitude of the resistive force acting in the opposite direction of their velocity also increases.
What two forces are in opposition when an object reaches terminal velocity?
The two opposing forces are a constant driving force (like gravity) and the velocity-dependent resistive force.
If an object is already moving at its terminal velocity and the constant downward force is suddenly removed, what happens to its motion?
The object will immediately begin to slow down because the only remaining force is the resistive force, which opposes its velocity and causes deceleration.