Physics Lesson 10 Newtons Third Law of Motion

  • Slides: 94
Download presentation
Physics Lesson 10 Newton’s Third Law of Motion – Action & Reaction Eleanor Roosevelt

Physics Lesson 10 Newton’s Third Law of Motion – Action & Reaction Eleanor Roosevelt High School Chin-Sung Lin

Review – Newton’s First Law of inertia Every object continues in a state of

Review – Newton’s First Law of inertia Every object continues in a state of rest, or of motion in a straight line at constant speed, unless it is compelled to change that state by an unbalanced force exerted upon it

No Unbalanced Force No unbalanced force means the net force = 0 Fnet =

No Unbalanced Force No unbalanced force means the net force = 0 Fnet = 0 Stay at Rest or Constant Velocity

Review - Newton’s Second Law of Force & Acceleration The acceleration produced by a

Review - Newton’s Second Law of Force & Acceleration The acceleration produced by a net force on an object is directly proportional to the magnitude of the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object

Unbalanced Force Unbalanced force means the net force ≠ 0 Fnet ≠ 0 F

Unbalanced Force Unbalanced force means the net force ≠ 0 Fnet ≠ 0 F m Fnet = m a a

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law Example

Newton’s Third Law of Action & Reaction (or Interaction) Whenever one object exerts a

Newton’s Third Law of Action & Reaction (or Interaction) Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object To every action there is always an equal opposing reaction

Newton’s Third Law Action force = Reaction force Faction = Freaction

Newton’s Third Law Action force = Reaction force Faction = Freaction

Newton’s Third Law Action and reaction forces are acting on different objects It doesn’t

Newton’s Third Law Action and reaction forces are acting on different objects It doesn’t matter which one is called action and which one is called reaction Force is not something an object has, like mass. Force is an interaction between two objects There cannot be action force without a reaction force

System Concept A systems is a coherent entity which has certain function A system

System Concept A systems is a coherent entity which has certain function A system can be characterized and described by its input and output, and the relation between them A system can be viewed as a collection of interconnected subsystems

Example: Identify the Interaction

Example: Identify the Interaction

Example: Identify the Interaction Earth attracts the vase Fg

Example: Identify the Interaction Earth attracts the vase Fg

Example: Identify the Interaction Earth attracts the vase The vase attracts Earth Fg

Example: Identify the Interaction Earth attracts the vase The vase attracts Earth Fg

Example: Identify the Interaction The table supports the vase FN

Example: Identify the Interaction The table supports the vase FN

Example: Identify the Interaction The table supports the vase The vase pushes the table

Example: Identify the Interaction The table supports the vase The vase pushes the table FN

Example: Identify the Interaction Fg FN

Example: Identify the Interaction Fg FN

Example: Identify the Interaction If the vase is our focus (or system) Fg FN

Example: Identify the Interaction If the vase is our focus (or system) Fg FN

Example: Identify the Interaction If the vase is our focus (or system) Fg =

Example: Identify the Interaction If the vase is our focus (or system) Fg = F N Fg FN

Exercise: Identify the Interaction

Exercise: Identify the Interaction

Exercise: Identify the Interaction Fg

Exercise: Identify the Interaction Fg

Exercise: Identify the Interaction FT

Exercise: Identify the Interaction FT

Exercise: Identify the Interaction FT Fg

Exercise: Identify the Interaction FT Fg

Exercise: Identify the Interaction FT Fg

Exercise: Identify the Interaction FT Fg

Exercise: Identify the Interaction FT Fg = F T Fg

Exercise: Identify the Interaction FT Fg = F T Fg

Newton’s Third Law Action force = Reaction force Faction = Freaction Do they cancel

Newton’s Third Law Action force = Reaction force Faction = Freaction Do they cancel each other out?

Why Does the Man-Box Move? A Man-Box System

Why Does the Man-Box Move? A Man-Box System

Why Does the Man-Box Move? A Man-Box System Horizontal forces only

Why Does the Man-Box Move? A Man-Box System Horizontal forces only

Why Does the Man-Box Move? A Man System Horizontal forces only

Why Does the Man-Box Move? A Man System Horizontal forces only

Why Does the Man-Box Move? A Box System Horizontal forces only

Why Does the Man-Box Move? A Box System Horizontal forces only

Why Does the Man-Box Move? A Man-Box System Horizontal forces only

Why Does the Man-Box Move? A Man-Box System Horizontal forces only

Newton’s Third Law Action force = Reaction force Faction = Freaction They do not

Newton’s Third Law Action force = Reaction force Faction = Freaction They do not cancel each other out since they are acting on the different objects

Why Does the Horse-Cart Move? A Horse-Cart System

Why Does the Horse-Cart Move? A Horse-Cart System

Why Does the Horse-Cart Move? A Horse-Cart System Horizontal forces only

Why Does the Horse-Cart Move? A Horse-Cart System Horizontal forces only

Why Does the Horse Move? A Horse System Horizontal forces only

Why Does the Horse Move? A Horse System Horizontal forces only

Why Does the Horse Move? A Horse System Horizontal forces only

Why Does the Horse Move? A Horse System Horizontal forces only

Why Does the Cart Move? A Cart System Horizontal forces only

Why Does the Cart Move? A Cart System Horizontal forces only

Why Does the Cart Move? A Cart System Horizontal forces only

Why Does the Cart Move? A Cart System Horizontal forces only

Why Does the Horse-Cart Move? A Horse-Cart System Horizontal forces only

Why Does the Horse-Cart Move? A Horse-Cart System Horizontal forces only

Why Does the Horse-Cart Move? A Horse-Cart System Horizontal forces only

Why Does the Horse-Cart Move? A Horse-Cart System Horizontal forces only

Exercise: Identify the Interaction A Rear Wheel Drive Car

Exercise: Identify the Interaction A Rear Wheel Drive Car

Exercise: Identify the Interaction A Front Wheel Drive Car

Exercise: Identify the Interaction A Front Wheel Drive Car

Exercise: Identify the Interaction

Exercise: Identify the Interaction

Exercise: Identify the Interaction A 100 N pushing force at 30 o angle is

Exercise: Identify the Interaction A 100 N pushing force at 30 o angle is exerted on a 10 kg block against the wall. Identify and calculate all the forces acting on the block by drawing the freebody diagram 100 N 30 o 10 kg

Exercise: Identify the Interaction 100 N 30 o 10 kg

Exercise: Identify the Interaction 100 N 30 o 10 kg

Newton’s Third Law Action force = Reaction force Faction = Freaction m 1 a

Newton’s Third Law Action force = Reaction force Faction = Freaction m 1 a 1 = m 2 a 2

Interaction on Different Masses

Interaction on Different Masses

Interaction on Different Masses

Interaction on Different Masses

Interaction on Different Masses 50 kg 2 m/s 2 40 kg a=?

Interaction on Different Masses 50 kg 2 m/s 2 40 kg a=?

Interaction through a String The reading of the scale is 50 N reading of

Interaction through a String The reading of the scale is 50 N reading of the scale? The mass of the object is 5 kg reading of the scale?

Interaction through a String reading of the scale?

Interaction through a String reading of the scale?

Interaction through a String MA = MB = 5 kg FTA = ? FTC

Interaction through a String MA = MB = 5 kg FTA = ? FTC = ? MC = ?

Interaction through a String m 10 kg 20 kg

Interaction through a String m 10 kg 20 kg

Interaction through a String M 2 = 5 kg T Θ = 30 o

Interaction through a String M 2 = 5 kg T Θ = 30 o

Interaction with acceleration At rest or constant speed a = 0 m/s 2

Interaction with acceleration At rest or constant speed a = 0 m/s 2

Interaction with acceleration At rest or constant speed Fg a = 0 m/s 2

Interaction with acceleration At rest or constant speed Fg a = 0 m/s 2

Interaction with acceleration At rest or constant speed Fg FN a = 0 m/s

Interaction with acceleration At rest or constant speed Fg FN a = 0 m/s 2 FN = F g Scale Reading

Interaction with acceleration Accelerate upward a

Interaction with acceleration Accelerate upward a

Interaction with acceleration Accelerate upward Fg a

Interaction with acceleration Accelerate upward Fg a

Interaction with acceleration Accelerate upward Fg FN a FN > F g Scale Reading

Interaction with acceleration Accelerate upward Fg FN a FN > F g Scale Reading

Interaction with acceleration Accelerate downward a

Interaction with acceleration Accelerate downward a

Interaction with acceleration Accelerate downward Fg FN a FN < F g Scale Reading

Interaction with acceleration Accelerate downward Fg FN a FN < F g Scale Reading

Interaction with acceleration Accelerate Downward with a=g

Interaction with acceleration Accelerate Downward with a=g

Interaction with acceleration Accelerate Downward with a=g Fg a=g

Interaction with acceleration Accelerate Downward with a=g Fg a=g

Interaction with acceleration Accelerate Downward with a=g Fg a=g FN = 0 N Scale

Interaction with acceleration Accelerate Downward with a=g Fg a=g FN = 0 N Scale Reading = 0 N

Interaction with acceleration

Interaction with acceleration

Interaction with acceleration

Interaction with acceleration

Interaction with acceleration Reading?

Interaction with acceleration Reading?

Interaction with acceleration m 1 = 10 kg T=? a = 2 m/s 2

Interaction with acceleration m 1 = 10 kg T=? a = 2 m/s 2 Frictionless m 2 = ?

Newton’s Third Law Video

Newton’s Third Law Video

Summary Newton’s third law - Faction = Freaction Every action always pairs with an

Summary Newton’s third law - Faction = Freaction Every action always pairs with an equal opposing reaction Action and reaction forces won’t cancel out each other since they are acting on different objects Identify the interactions Use system concept and free-body diagram to identify the forces exerting on a system

Summary Use system concept and free-body diagram to explain motion Interaction on different masses

Summary Use system concept and free-body diagram to explain motion Interaction on different masses m 1 a 1 = m 2 a 2 Interaction through a string - Tension Interaction with acceleration