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: 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 2: State whether static friction depends on the surface area of contact.

Answer: No, it does not depend on surface area. Friction depends only on materials and normal force.

Flashcard 3: Find the static friction if $\text{μ}_s = 0.5$ and $N = 40 \text{ N}$.

Answer: $f_s \text{ (max)} = 20 \text{ N}$. Using $f_s = \text{μ}_s N = 0.5 \times 40 = 20$ N.

Flashcard 4: Define the coefficient of kinetic friction.

Answer: The ratio of kinetic friction force to the normal force. Shows how friction scales with normal force for moving objects.

Flashcard 5: 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 6: What is the formula for the force of static friction?

Answer: $f_s \text{ (max)} = \text{μ}_s N$. Maximum static friction equals coefficient times normal force.

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: State whether static friction depends on the surface area of contact.

Answer: No, it does not depend on surface area. Friction depends only on materials and normal force.

Flashcard 9: Identify the friction type when an object slides down a slope.

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

Flashcard 10: What does the symbol $N$ represent in friction formulas?

Answer: The normal force. Perpendicular contact force between surfaces.

Flashcard 11: Define the coefficient of kinetic friction.

Answer: The ratio of kinetic friction force to the normal force. Shows how friction scales with normal force for moving objects.

Flashcard 12: State whether kinetic friction depends on the surface area of contact.

Answer: No, it does not depend on surface area. Friction depends only on materials and normal force.

Flashcard 13: What is the primary force opposing motion on a flat surface?

Answer: Friction. Friction opposes relative motion between surfaces.

Flashcard 14: Identify the friction type when pushing an object that does not move.

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

Flashcard 15: State whether kinetic friction depends on the surface area of contact.

Answer: No, it does not depend on surface area. Friction depends only on materials and normal force.

Flashcard 16: 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 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: 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 19: Identify the type of friction that occurs when an object is in motion.

Answer: Kinetic friction. Acts on objects that are sliding.

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: 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 22: 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 23: What effect does lubrication have on kinetic friction?

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

Flashcard 24: What effect does lubrication have on static friction?

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

Flashcard 25: 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 26: 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 27: How does surface roughness affect the coefficients of friction?

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

Flashcard 28: 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 29: What does a higher coefficient of friction indicate?

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

Flashcard 30: 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 31: What does the symbol $f_s$ represent?

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

Flashcard 32: What effect does lubrication have on static friction?

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

Flashcard 33: What is the effect of increasing the mass on normal force?

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

Flashcard 34: What effect does lubrication have on kinetic friction?

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

Flashcard 35: What does the symbol $f_k$ represent?

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

Flashcard 36: 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 37: Identify the type of friction that occurs when an object is at rest.

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

Flashcard 38: What is the primary force opposing motion on a flat surface?

Answer: Friction. Friction opposes relative motion between surfaces.

Flashcard 39: Which option best describes friction between tires and a road while driving?

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

Flashcard 40: What condition must be met for static friction to be at its maximum value?

Answer: The object is on the verge of motion. When applied force equals maximum static friction.

Flashcard 41: What is the formula for the force of kinetic friction?

Answer: $f_k = \mu_k N$. Kinetic friction equals coefficient times normal force.

Flashcard 42: Which is usually larger, $\text{μ}_s$ or $\text{μ}_k$?

Answer: $\text{μ}_s$ is usually larger. It takes more force to start motion than maintain it.

Flashcard 43: Identify the type of friction that occurs when an object is at rest.

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

Flashcard 44: 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 45: How does surface roughness affect the coefficients of friction?

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

Flashcard 46: What is the unit of measurement for the coefficients of friction?

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

Flashcard 47: Which option best describes friction between tires and a road while driving?

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

Flashcard 48: 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 49: 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 50: What is the unit of measurement for the coefficients of friction?

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

Flashcard 51: 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 52: What is the effect of increasing the mass on normal force?

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

Flashcard 53: What condition must be met for static friction to be at its maximum value?

Answer: The object is on the verge of motion. When applied force equals maximum static friction.

Flashcard 54: 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 55: What does $\text{μ}$ depend on?

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

Flashcard 56: 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 57: Identify the type of friction that occurs when an object is in motion.

Answer: Kinetic friction. Acts on objects that are sliding.

Flashcard 58: 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 59: 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 60: What is the formula for the force of static friction?

Answer: $f_s \text{ (max)} = \text{μ}_s N$. Maximum static friction equals coefficient times normal force.

Flashcard 61: Identify the friction type when an object slides down a slope.

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

Flashcard 62: 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 63: What does the symbol $f_s$ represent?

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

Flashcard 64: 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 65: What does the symbol $N$ represent in friction formulas?

Answer: The normal force. Perpendicular contact force between surfaces.

Flashcard 66: What does a higher coefficient of friction indicate?

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

Flashcard 67: Which option best describes friction between a sled and snow while sliding?

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

Flashcard 68: Which is usually larger, $\text{μ}_s$ or $\text{μ}_k$?

Answer: $\text{μ}_s$ is usually larger. It takes more force to start motion than maintain it.

Flashcard 69: Find the static friction if $\text{μ}_s = 0.5$ and $N = 40 \text{ N}$.

Answer: $f_s \text{ (max)} = 20 \text{ N}$. Using $f_s = \text{μ}_s N = 0.5 \times 40 = 20$ N.

Flashcard 70: Which option best describes friction between a sled and snow while sliding?

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

Flashcard 71: 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 72: 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 73: 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 74: 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 75: What does $\text{μ}$ depend on?

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

Flashcard 76: What does the symbol $f_k$ represent?

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

Flashcard 77: 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.