AP Physics 1 Flashcards: Kinetic And Static Friction

What this deck covers

This deck focuses on Kinetic And Static Friction, giving you a quick way to review the definitions, rules, and examples that matter most for AP Physics 1.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What effect does lubrication have on static friction?

Answer: It reduces static friction. Lubrication decreases friction between surfaces.

Flashcard 2: If $f_s = 15 \text{ N}$ and $N = 50 \text{ N}$, find $\text{μ}_s$.

Answer: $\text{μ}_s = 0.3$. Using $\text{μ}_s = f_s/N = 15/50 = 0.3$.

Flashcard 3: If $f_k = 10 \text{ N}$ and $N = 50 \text{ N}$, find $\text{μ}_k$.

Answer: $\text{μ}_k = 0.2$. Using $\text{μ}_k = f_k/N = 10/50 = 0.2$.

Flashcard 4: How does surface roughness affect the coefficients of friction?

Answer: Increases both coefficients. Rougher surfaces create more friction.

Flashcard 5: Determine the normal force on a $5 \text{ kg}$ object on a flat surface.

Answer: $N = 49 \text{ N}$. Using $N = mg = 5 \times 9.8 = 49$ N.

Flashcard 6: If $f_k = 10 \text{ N}$ and $N = 50 \text{ N}$, find $\text{μ}_k$.

Answer: $\text{μ}_k = 0.2$. Using $\text{μ}_k = f_k/N = 10/50 = 0.2$.

Flashcard 7: If an object is moving at constant speed, what can be said about friction?

Answer: Kinetic friction equals the applied force. No net force means friction balances applied force.

Flashcard 8: Find kinetic friction if $\text{μ}_k = 0.1$ and $N = 250 \text{ N}$.

Answer: $f_k = 25 \text{ N}$. Using $f_k = \text{μ}_k N = 0.1 \times 250 = 25$ N.

Flashcard 9: What is the primary force opposing motion on a flat surface?

Answer: Friction. Friction opposes relative motion between surfaces.

Flashcard 10: What does $\text{μ}$ depend on?

Answer: Material properties of surfaces. Coefficient depends on surface materials and conditions.

Flashcard 11: If $\text{μ}_k = \text{μ}_s$, what can be inferred about motion?

Answer: Frictional resistance is constant during motion. Same friction force whether moving or stationary.

Flashcard 12: Identify the type of friction that occurs when an object is at rest.

Answer: Static friction. Acts on objects that aren't sliding.

Flashcard 13: Find the kinetic friction if $\text{μ}_k = 0.3$ and $N = 70 \text{ N}$.

Answer: $f_k = 21 \text{ N}$. Using $f_k = \text{μ}_k N = 0.3 \times 70 = 21$ N.

Flashcard 14: What does the symbol $f_k$ represent?

Answer: The force of kinetic friction. Standard notation for kinetic friction force.

Flashcard 15: What does the symbol $f_s$ represent?

Answer: The force of static friction. Standard notation for static friction force.

Flashcard 16: Which option best describes friction between a sled and snow while sliding?

Answer: Kinetic friction. Sled slides continuously across the surface.

Flashcard 17: Find static friction if $\text{μ}_s = 0.6$ and $N = 200 \text{ N}$.

Answer: $f_s \text{ (max)} = 120 \text{ N}$. Using $f_s = \text{μ}_s N = 0.6 \times 200 = 120$ N.

Flashcard 18: What happens to kinetic friction as the angle of an inclined plane increases?

Answer: Kinetic friction remains constant regardless of angle. Kinetic friction magnitude doesn't change with angle.

Flashcard 19: What is the effect of increasing the mass on normal force?

Answer: Normal force increases. More mass creates larger normal force.

Flashcard 20: Identify the friction type when pushing an object that does not move.

Answer: Static friction. Object remains at rest, so static friction acts.

Flashcard 21: What does a higher coefficient of friction indicate?

Answer: Greater resistance to motion. Higher coefficients mean more frictional force.

Flashcard 22: What effect does lubrication have on kinetic friction?

Answer: It reduces kinetic friction. Lubrication decreases friction between surfaces.

Flashcard 23: What is the unit of measurement for the coefficients of friction?

Answer: Dimensionless (no units). Coefficients are ratios of forces.

Flashcard 24: Find the maximum static friction if $\text{μ}_s = 0.4$ and $N = 50 \text{ N}$.

Answer: $f_s \text{ (max)} = 20 \text{ N}$. Using $f_s = \text{μ}_s N = 0.4 \times 50 = 20$ N.

Flashcard 25: Define the coefficient of static friction.

Answer: The ratio of maximum static friction force to the normal force. Shows how friction scales with normal force for stationary objects.

Flashcard 26: What happens to static friction as the angle of an inclined plane increases?

Answer: Static friction increases until the object starts to move. Adjusts to prevent sliding up to its maximum.

Flashcard 27: Which option best describes friction between tires and a road while driving?

Answer: Static friction. Tires grip the road without sliding.

Flashcard 28: Find the normal force if $m = 10 \text{ kg}$ and $g = 9.8 \text{ m/s}^2$ on a flat surface.

Answer: $N = 98 \text{ N}$. Using $N = mg = 10 \times 9.8 = 98$ N.

Flashcard 29: Find the kinetic friction if $\text{μ}_k = 0.2$ and $N = 100 \text{ N}$.

Answer: $f_k = 20 \text{ N}$. Using $f_k = \text{μ}_k N = 0.2 \times 100 = 20$ N.

Flashcard 30: Identify the friction type when an object slides down a slope.

Answer: Kinetic friction. Object is moving, so kinetic friction acts.