professor-curious-logo
professor-curious-logo
  2. AP Physics C Mechanics
FlashcardFlashcard
Study GuideStudy GuideQuestion BankQuestion BankGlossaryGlossary

What is a resistive force?

A force that opposes the motion of an object, slowing it down. It is velocity-dependent and acts in the opposite direction of motion.

Flip to see [answer/question]
Flip to see [answer/question]
Revise later
SpaceTo flip
If confident

All Flashcards

What is a resistive force?

A force that opposes the motion of an object, slowing it down. It is velocity-dependent and acts in the opposite direction of motion.

Define terminal velocity.

The maximum speed an object reaches when the constant force (like gravity) and the resistive force (like air resistance) balance each other, resulting in zero net acceleration.

What is the time constant (τ\tauτ)?

The time constant, τ=mk\tau = \frac{m}{k}τ=km​, indicates how quickly an object reaches terminal velocity. A larger mass or smaller k (weaker resistive force) means a longer time to reach terminal speed.

Define kkk in the context of resistive force.

kkk is a positive constant that depends on the shape and size of the object and the properties of the medium (like air density). It appears in the resistive force equation: F⃗r=−kv⃗\vec{F}_{r} = -k \vec{v}Fr​=−kv

What is the relationship between net force and acceleration at terminal velocity?

At terminal velocity, the net force is zero, which means the acceleration is also zero. The object stops speeding up.

What are the general steps to solve for velocity with resistive forces?

  1. Apply Newton's Second Law ((F_{net} = ma)). 2. Set up the differential equation for velocity. 3. Use separation of variables. 4. Integrate to find the velocity function. 5. Apply initial conditions to solve for constants.

How do you find terminal velocity mathematically?

  1. Set the net force equal to zero (resistive force + gravitational force = 0). 2. Solve for velocity ((v_t)), which represents terminal velocity.

What happens to velocity, acceleration, and net force as time approaches infinity when an object experiences air resistance?

  1. Velocity approaches terminal velocity (constant value). 2. Acceleration approaches zero. 3. Net force approaches zero.

What are the steps to determine how quickly an object reaches terminal velocity?

  1. Calculate the time constant, τ=mk\tau = \frac{m}{k}τ=km​. 2. A larger mass or smaller k (weaker resistive force) means a longer time to reach terminal speed.

How do you analyze motion with varying resistive forces?

  1. Draw a free-body diagram to identify all the forces acting on the object. 2. Write out the differential equation and then solve it step-by-step.

What is the difference between motion with and without resistive forces?

Without resistive forces: motion continues indefinitely (Newton's First Law) or accelerates constantly. With resistive forces: motion slows down, reaches terminal velocity, and acceleration approaches zero.

Compare the terminal velocity of a skydiver in a spread-eagle position versus a streamlined dive.

Spread-eagle: Lower terminal velocity due to greater surface area and air resistance. Streamlined dive: Higher terminal velocity due to less surface area and air resistance.

What is the difference between heavier and lighter objects in terms of terminal velocity?

Heavier objects: Greater terminal velocities because they have a larger gravitational force to balance against air resistance. Lighter objects: Lower terminal velocities because they have a smaller gravitational force.

Differentiate between initial velocity and terminal velocity.

Initial velocity: The velocity of an object at the start of its motion. Terminal velocity: The maximum speed achieved when forces balance.

Compare the effect of a larger mass vs. a smaller k on the time to reach terminal speed.

Larger mass: Longer time to reach terminal speed. Smaller k: Weaker resistive force, longer time to reach terminal speed.