1.2.3 Friction

• What does static friction oppose?

  The start of motion
• Order the types of friction from most opposing to least opposing:

  1️⃣ Static Friction

  2️⃣ Kinetic Friction

  3️⃣ Rolling Friction
• What are the three primary types of friction?

  Static, kinetic, rolling
• How does increasing surface roughness affect friction?

  It increases friction
• Increasing the surface area between two surfaces increases friction


  True
• Arrange the interactions between friction and Newton's Laws in the correct sequence:

  1️⃣ Friction brings an object at constant velocity to rest.

  2️⃣ Friction reduces the acceleration of an object.

  3️⃣ Friction acts on both surfaces in contact.
• How does friction enable us to walk, run, and climb?

  Provides traction
• Friction between a pen and paper allows us to write.
• Friction reduces the efficiency of machines by causing energy losses.

  True
• How does lubrication reduce friction between surfaces?

  Creates a smooth sliding layer
• Friction is a force that opposes the relative motion between two surfaces in contact
• Increasing the roughness of a surface decreases friction.

  False
• What happens to friction when the surface area between two objects increases?

  It increases
• What is an example of kinetic friction in everyday life?

  A book sliding on a table
• What are the main factors that affect the amount of friction?

  Surface area, roughness, normal force
• How does increasing the normal force affect friction?

  Increases friction
• Which law explains how friction reduces the acceleration of an object?

  Newton's Second Law
• What is the net force on a 5 kg box pushed with a 20 N force across a surface with a 5 N frictional force?

  15 N
• What is an example of friction holding objects in place?

  A book on a table
• How does friction contribute to wear and tear on moving parts?

  Opposes motion
• Arrange the methods to reduce friction in order of their effectiveness:

  1️⃣ Lubrication

  2️⃣ Surface Smoothing

  3️⃣ Using Bearings or Rollers

  4️⃣ Smooth Surface Design

  5️⃣ Coatings
• What is friction defined as?

  A force opposing motion
• What does kinetic friction oppose?

  Sliding motion
• Increasing the normal force between two surfaces will increase the friction
• What is an example of static friction in everyday life?

  A box on the floor
• The normal force is the force perpendicular to the two surfaces in contact
• Increasing the roughness of surfaces increases friction.
• Friction brings an object at constant velocity to rest, as described by Newton's First Law.


  True
• Match the law with its role in friction:

  Newton's First Law ↔️ Brings an object moving at constant velocity to rest.

  Newton's Second Law ↔️ Reduces the acceleration of an object.

  Newton's Third Law ↔️ Friction acts on both surfaces in contact.
• A 5 kg box with a net force of 15 N has an acceleration of 3 m/s².
• Friction in brakes opposes motion to slow down vehicles.

  True
• What is an example of friction leading to undesirable heating?

  Car brakes
• Rolling friction is significantly less resistant than sliding friction.


  True