3.3 Forces and Newton's Laws

• What is the definition of a force?

  Interaction causing motion change
• How are forces combined when they act on an object?

  Vector addition
• Order the steps involved in vector addition of two forces acting at an angle.

  1️⃣ Draw the force vectors head-to-tail

  2️⃣ Calculate the magnitude of the resultant force

  3️⃣ Determine the direction of the resultant force
• Inertia is an object's resistance to changes in its motion
• What is the distinguishing feature of vector quantities compared to scalars?

  Direction
• What is another name for Newton's First Law of Motion?

  Law of Inertia
• What is the relationship between an object's mass and its inertia?

  Directly related
• What unit is used to measure force in Newton's Second Law?

  Newtons
• If a 2 kg object experiences a 10 N force, its acceleration is 5 m/s².

  True
• Action and reaction forces are equal in magnitude but opposite in direction.


  True
• Steps to draw a free body diagram

  1️⃣ Isolate the object of interest

  2️⃣ Identify all the forces acting on the object

  3️⃣ Draw arrows to represent each force
• Translational equilibrium occurs when the net force on an object is zero.

  True
• Rotational equilibrium requires the net torque on the object to be zero.


  True
• Vector addition of forces can be done graphically or algebraically.


  True
• What formula represents Newton's Second Law of Motion?

  $F =$$ma$
• The formula for Newton's Second Law is $F =$$ma$


  True
• Newton's Third Law is also known as the Law of Action-Reaction.


  True
• Free body diagrams depict the magnitude and direction of forces acting on an object.


  True
• Equilibrium occurs when the net force acting on an object is zero.


  True
• In three dimensions, equilibrium is achieved when the sums of the force components in all three directions are zero.


  True
• A book resting on a table is an example of translational equilibrium.


  True
• Match the type of equilibrium with its conditions:

  Translational Equilibrium ↔️ $\Sigma F_{x} =$$0, \Sigma F_{y} =$$0, \Sigma F_{z} =$$0$

  Rotational Equilibrium ↔️ $\Sigma \tau =$$0$
• The unit for measuring force is the Newton
• Scalar quantities have magnitude but no direction
• What is the key difference between vector and scalar quantities?

  Direction
• When the net force on an object is zero, it is in equilibrium.


  True
• What is another name for Newton's First Law of Motion?

  Law of Inertia
• Inertia is an object's resistance to changes in its motion
• Match the property with its definition:

  Inertia ↔️ Resistance to changes in motion

  Mass ↔️ Measure of the amount of matter

  Force ↔️ Interaction that causes motion change
• What is another name for Newton's Third Law of Motion?

  Law of Action-Reaction
• Match the property of action and reaction forces:

  Magnitude ↔️ Equal

  Direction ↔️ Opposite

  Act on ↔️ Different objects
• What is the condition for equilibrium in terms of net force?

  Net force is zero
• Equilibrium occurs when the net force acting on an object is zero
• What is the unit of force?

  Newton
• What is another name for Newton's First Law of Motion?

  Law of Inertia
• The greater the force applied, the greater the acceleration
• What unit is used to measure force in Newton's Second Law?

  Newtons
• What two properties do action-reaction forces always have?

  Equal magnitude, opposite direction
• Steps to draw a free body diagram

  1️⃣ Isolate the object of interest

  2️⃣ Identify all the forces acting on the object

  3️⃣ Draw arrows to represent each force
• In two dimensions, equilibrium is achieved when the sum of forces in the x and y directions is zero