2.9 Resistive Forces

• What opposes the motion of an object through a medium?

  Resistive forces
• What are the two types of frictional forces?

  Static and kinetic
• Which type of resistive force is proportional to velocity?

  Linear
• What type of resistive force arises from interaction with a solid surface?

  Friction
• What does $\mu_{k}$ represent in the kinetic friction equation?


  Kinetic friction coefficient
• At high speeds, the quadratic drag force dominates over linear friction.

  True
• Drag forces oppose the motion of an object through a fluid
• Give an example where air resistance is significant.

  Car moving through air
• Order the following steps to calculate the linear drag force:

  1️⃣ Determine the drag coefficient b

  2️⃣ Measure the object's velocity $\vec{v}$

  3️⃣ Calculate $\vec{F} =$$- b\vec{v}$
• The linear drag force equation is $\vec{F} =$$- b\vec{v}$, where $b$ is the drag coefficient
• What is the dependence of linear resistive force on velocity?

  Proportional
• What type of resistive force arises from the interaction with a solid surface?

  Friction
• Order the steps to calculate air resistance on a car:

  1️⃣ Determine the drag coefficient C

  2️⃣ Measure the car's velocity $\vec{v}$

  3️⃣ Calculate $\vec{F}_{drag} =$$- C|\vec{v}|^{2}\hat{v}$
• What is the drag force equation for air resistance?

  $\vec{F}_{drag} =$$- C|\vec{v}|^{2}\hat{v}$
• The constant $C$ in the drag force equation for fluid resistance depends on different fluid properties
• What happens to terminal velocity if mass increases?

  Increases
• What type of frictional force opposes the initial motion of an object?

  Static friction
• What is the force equation for kinetic friction?

  $\vec{F}_{k} =$$- \mu_{k}N\hat{v}$
• What is the equation for static friction?

  \vec{F}_{s} = - \mu_{s}N\hat{v}</latex>
• What are resistive forces proportional to?

  Object's velocity
• Linear resistive forces are common in viscous fluids.


  True
• Drag force is proportional to the square of the object's velocity.
• Air resistance depends on the object's shape, size, and the density of the air


  True
• The drag force is the resistance experienced by an object moving through a fluid
• How does higher mass affect terminal velocity?

  Increases it
• What are the two types of frictional forces?

  Static and kinetic
• Kinetic friction acts to slow down a moving object

  True
• The coefficient of static friction is denoted by the symbol \mu_{s}
• Static friction opposes continued motion, while kinetic friction opposes initial motion.

  False
• When a ball falls through a fluid, it reaches terminal velocity
• Match the resistive force with its formula:

  Linear Drag ↔️ $\vec{F} =$$- b\vec{v}$

  Quadratic Drag ↔️ $\vec{F} =$$- C|\vec{v}|^{2}\hat{v}$

  Static Friction ↔️ $\vec{F} =$$- \mu_{s}N\hat{v}$

  Kinetic Friction ↔️ $\vec{F} =$$- \mu_{k}N\hat{v}$
• Terminal velocity is achieved when the net force on an object is zero.

  True
• Match the type of resistive force with its equation:

  Linear ↔️ $\vec{F} =$$- b\vec{v}$

  Quadratic ↔️ $\vec{F} =$$- C|\vec{v}|^{2}\hat{v}$
• Drag is proportional to the square of the object's velocity.


  True
• Kinetic friction is described by $\vec{F} =$$- \mu_{k} m g \hat{v}$.


  True
• What type of fluid is associated with drag forces?

  Air
• Air resistance depends on the object's shape, size, and air density.


  True
• Match the type of drag force with its example:

  Air resistance ↔️ Car moving through air

  Fluid resistance ↔️ Submarine underwater
• Match the type of drag force with its equation:

  Linear drag ↔️ $\vec{F} =$$- b\vec{v}$

  Quadratic drag ↔️ $\vec{F} =$$- C|\vec{v}|^{2}\hat{v}$
• Drag force is proportional to the square of the object's velocity.


  True