2.2 Forces and Free-Body Diagrams

• Non-contact forces include gravitational force, electric force, and magnetic
• What does Newton's Third Law describe about forces?

  Equal and opposite pairs
• Non-contact forces require physical interaction between objects.

  False
• What is the purpose of a free-body diagram?

  Identify and analyze forces
• What is a force defined as in physics?

  An interaction between objects
• How do non-contact forces act between objects?

  Through fields
• An object at rest stays at rest unless acted upon by a net external force.
• Match Newton's Third Law with its example:

  Action ↔️ Pushing a wall

  Reaction ↔️ The wall pushes back
• The gravitational force is an attractive force between objects due to their mass.
• What is the primary mechanism by which non-contact forces act?

  Through fields
• What is a force defined as in physics?

  An interaction between objects
• Newton's Second Law states that F = ma.


  True
• Match the contact force with its definition:

  Normal Force ↔️ Force exerted by a surface

  Friction ↔️ Force opposing motion

  Tension ↔️ Force through a string

  Applied Force ↔️ Force directly applied
• The gravitational force is an attractive force between objects due to their mass
• Steps for using a free-body diagram

  1️⃣ Identify all forces acting on the object

  2️⃣ Draw arrows representing the forces

  3️⃣ Label each force with its type

  4️⃣ Determine the net force
• Forces that require direct physical contact between objects are called contact forces.
• Newton's Three Laws of Motion describe how forces cause changes in motion.


  True
• What does Newton's Second Law state in mathematical terms?

  $F =$$ma$
• What is the normal force exerted by a surface on an object?

  Support force
• Non-contact forces require physical contact between objects.

  False
• Steps in using a free-body diagram to analyze motion:

  1️⃣ Identify all forces acting on an object

  2️⃣ Determine the net force

  3️⃣ Apply Newton's Laws to analyze motion
• A box resting on a horizontal surface has a net force of zero in the vertical direction.


  True
• Free-body diagrams are an essential tool in physics
• A free-body diagram is used to analyze the motion of an object using Newton's Laws.

  True
• What are two types of forces that can act on an object?

  Contact and non-contact
• The net force in a free-body diagram is determined by adding all individual force vectors.

  True
• What does Fn represent in a free-body diagram for a book on a table?

  Normal force
• In a free-body diagram for a block sliding down an inclined plane, the normal force balances the weight completely.

  False
• How is the net force determined in a free-body diagram?

  By adding all force vectors
• A free-body diagram is used to identify all the forces
• The normal force on an object is always equal to its weight.

  False
• Steps to draw a free-body diagram

  1️⃣ Identify all the forces acting on the object

  2️⃣ Draw the object as a simple shape

  3️⃣ Represent each force as an arrow

  4️⃣ Determine the net force
• The first step in solving force problems using free-body diagrams is to draw the free-body diagram
• Which of Newton's Laws is applied when an object is in equilibrium?

  Newton's First Law
• The friction force is calculated as the coefficient of friction multiplied by the normal
• What is the purpose of identifying forces in a free-body diagram?

  To understand their effects
• What forces are shown in a free-body diagram for a book resting on a table?

  Normal force and weight
• For a book resting on a table, the free-body diagram would show the normal force and the gravitational force acting on the book.
• Steps to draw a free-body diagram

  1️⃣ Identify all the forces acting on the object

  2️⃣ Draw the object as a simple shape

  3️⃣ Represent each force as an arrow

  4️⃣ Determine the net force
• In a free-body diagram, forces are represented as arrows pointing in the appropriate direction.