Notes: Name: __________________________

Stamps:

Directions: Fill in the blanks and boxes in the note panel. After notes are done, part of your homework is to fill in the sides with study questions and write a summary that demonstrates you understand what is important in the notes.

Inertia, Newton’s 1st Law and ForcesQuestions/Main Ideas Main Notes

Force ________ or a _______

o Contact Force physical contacto Field Forces No contact: gravity, magnetic force, etc.

Newton’s First Law:

• An object wants to _________________________________________

__________________________________________________________

• In order to change, it needs a _________________ not equal to zero

= Sum of all forces.

Weight is a force. Mass is not a force.

Weight is a force exerted by ___________ on an objects mass.

Weight can change if gravity changes (which would happen if went to a different planet!)

Mass Weight

A measure of how much _________ makes up an object.

Mass depends on the object itself, it never changes!

Mass is a measure of inertia

Mass is measured in: _______

Weight is a _________!

Weight depends on an objects acceleration due to gravity

Weight is measured in: ________ or pounds (lbs)

Summary:

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NOTES NEWTON’S LAWS –MOTION

Free Body DiagramsQuestions/Main Ideas Main Notes

Free Body Diagram Guidelines

1. Identify all __________ acting upon an object

Force: a push or a pull

2. Arrows indicate __________ and relative _________ of forces

3. Vectors originate from the ________________

Scenario 1: 10 kg block in falling at terminal velocity

Scenario 2: 10 kg block pulled across a frictionless floor by a string

Possible Forces

o Appliedo Air resistance / Drago Frictiono Gravity / Weighto Normalo Tensiono Thrust

Net force = zero because terminal velocity is maximum speed (no acceleration)

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Scenario 3: 1000 kg car moving right, using its breaks to slow down on a level freeway. Consider friction.

Scenario 4: 10 kg block on a frictionless ramp at 30°

• Choose x and y to line up with most __________

• Weight has both an x and y component

• The angle between the weight and Fy is the same as the angle between the ramp and the ground

• _____ (b/c the block does not accelerate in the y direction)

• Only force left is the ____________________ of the weight

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Σ F y=

Σ Fx=

Air Resistance

• Two things determine amount of air resistance:

• ___________________

• ___________

Summary of possible forces

Force Variable Direction

Applied Direction of push/pull

Air resistance / Drag

Friction Opposite to motion

Fw or Fg

FN or N

FT or T Towards center of rope/string/cable

Thrust

Summary:

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2nd LawQuestions/Main Ideas Main Notes

Recap of 1st law:

• involves objects with no _________________

• When you do have a _________________:

• object will ________________ in same direction

• This _______________ is proportional to the _____________

and inversely proportional to its _____________

Put the two together:

• mass units: ___________

• acceleration units: ___________

• This makes force units: ___________

• Let’s call ___________a ___________ (____)

Lab Prep

1. Draw a Free Body Diagram of the moving “body”

2. Which forces affect the motion?

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Freefalling

• __________ is a very common force

•In freefalling the only force is _________ (assuming no air resistance)

•In freefall, the acceleration of gravity is __________ (___)

• But most objects DO NOT accelerate at ______!

• For example: FAir resistance causes falling objects accelerate __________

o in fact, when FAir resistance = Fw the object’s a =_____

• This is because of _________

Example:The Batman, with a mass of 70-kg, rappels down a rope from hisbat-copter with a downward acceleration of 3.5 m/s2. What vertical force does the rope exert on Batman?

1. Start all force questions with free body diagram2. Pick the positive direction

Summary:

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3rd LawQuestions/Main Ideas Main Notes

• Equal and _____________

• For every force that one object __________ on a second

object, the second object ___________ an equal (________)

and opposite (__________) reaction force on the first object

• Forces only come in ________ (you cannot create a

________ force)

• Does action cancel out reaction?

• ______! Each force acts on a _____________ object.

• Each force has _____________ effect on their object!

(ex. ________________)

Summary:

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FrictionQuestions/Main Ideas Main Notes

• Friction is ____________ there is motion on a ___________ or within

a ___________

• Friction is a _____________ force (a force that __________ motion)

• Friction evidence?

• Let’s examine ______________

• Even “smooth” sandpaper is ______________

• If you slide the surfaces of two pieces together

• Atoms at the peaks ________ with _________ at the peaks of the other

• It requires force to break these __________

• opposing force is ______________

Tribology

• The ________________ effect of friction was discovered by

________________ in the 1950’s

• a ________________ is someone who studies ______________

• Which would experience more friction, normal surfaces or very polished surfaces?

• _____________! There are way more ___________ that come into

___________ and make __________

• If surface is polished smoothly enough, it can create a _____________

known as ______________

• Almost impossible to ______________

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Force of friction

• Friction between solid surfaces depends on:

1. The ___________ (_______) force between the surfaces in contact

2. The __________ of the surfaces in contact

• together, these create a ________________ force

• Rub your hands together

• What happens to friction if you press harder?

• So, F

• When the object is on a surface _________ to Earth’s surface, N = ___

• Rub your hands together again

• What would happen to friction if you added some oil to your hands?

• What would happen to friction if you added some dry glue?

• This condition of a surface is given as a quantity known as the

_______________________ (____)

Nature of surfaces

• Each situation has _______ coefficients

• μs = _______________ friction

• when an object is being pushed, but hasn’t moved yet

• μk = _______________ friction

• the friction once the object starts _______________

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Frictional Force

• Friction is the product of the _____________ force and the coefficient of friction

• when μ = 0, surface contact is ______________

Example• Let’s compare the friction force of a 2,000N car skidding on a dry road compared to an icy one:

f dry=

f icy=

• That’s why it takes so long to ____________________

Summary:

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1st Law: Rotational StyleQuestions/Main Ideas Main Notes

Newton’s First Law:

• An object wants to _________________________________________

__________________________________________________________

• In order to change, it needs a _________________ not equal to zero

if ______ then, _______

Translational Motion: motion without ____________________

• ______________ can cause rotation

• If a force is applied to an object with a fulcrum, you get rotational

motion (torque)

• Fulcrum: ____________________

• Rotational Force is most effective _______________ the fulcrum

• Torque is the combination of _______________ and

distance ______________________

Which lever arm has the greatest torque?

A B C

• Only the _________________ part of the force is applied to the torque

• This require a touch of trigonometry

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A B

C D

E F

Rotational Stability

= =

=

F1 F2 F1

F2

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• “In the absence of a ______________, an object not rotating will

continue to ______________ and an object rotating will continue to

______________ at a constant _______________________”

• This means that if a rotational system is in _________________

(____________________), the net torque is ____________

• CW torques are _____________, CCW torques are _______________

Which dog has a positive torque?

Center Of Mass Concentration of mass

• Where the ___________________ of the object is located

• Weight force can add a __________ if it is not at the __________

• Where is the woman’s COM?

• In her upper body there are ___ main torques.

• To compensate she needs to ____________

Example:A 175 lb. father wants to let his 55 lb. daughter play on a seesaw as he buys some much needed coffee. Assume she sits at the end of the 10.0-foot long

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board. If the board has a weight of 100 lbs. where must he slide the board so that the board’s weight will balance her weight?

Summary:

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