On the white board… In your own words, how would you explain or describe FORCES?

Today we will Describe forces using task cards, Cornell Notes, and a concept map.

Forces Chapter 10

1. The nature of forces 2. Force – what is it? 3. Push or a pull 3. Has a magnitude and direction 3. SI unit is Newton (N) 4. Named after Sir Isaac Newton

2. Combining Forces 3. Net force – what is it? 4. Combination of all forces added together 4. Determines which direction an object moves 4. Determines if an object moves 4. Must take in the direction when adding them.

3. Examples What is the net force for the following problems? a.10 N4 N b.3 N6 N

STOP QUESTIONS – PERSON B BEGINS

2. Unbalanced forces 3. Net force will cause an object to change the object’s velocity. 3. Examples 4. People pushing a box 4. Swing 4.

2. Balanced Forces 3. Forces acting on an object that do not cause a change in the velocity of that object. 3. Examples 4. Two people pushing a box with equal force in opposite directions 4. Balancing a book on your head. 4.

STOP QUESTIONS – PERSON D BEGINS

In class strategy Create a concept map for the word … FORCE

Today we will… Explore various forces that could be acting on a bridge using the text book, Internet, and examples.

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Today we will… Discuss Friction, Gravity, and Elastic Forces using Cornell Notes and Choice Strategies.

1. Various forces and laws 2. Friction – what is it? 3. Force that two surfaces exert on each other when they rub against each other. 3. Strength of the force depends on the type of surface and how hard they push together

2. Types of friction 3. Static friction 4. Acts on objects that are not moving 3. Sliding friction 4. Two solid surfaces slide over each other 3. Rolling friction 4. When an object rolls across a surface 3. Fluid Friction 4. Solid object moves through fluid

2. Gravity 3. A force that pulls objects toward each other 3. Acts everywhere, not just Earth 4. Universal Law of Gravitation 3. Force between the objects increases with greater mass and decreases with greater distance

3. Weight = mass x gravity acceleration (9.8m/s 2 ) Mass = lbs / 2.2 Mass x 9.8 = your weight in N

2. Gravity and Motion 3. Free fall 4. The force of gravity alone causes an object to accelerate in the downward direction. 3. Air resistance 4. Fluid friction that acts on objects falling through the air 3. Projectile 4. Any object that is thrown.

2. Elastic forces 3. Matter is considered elastic if it returns to its original shape after it is squeezed or stretched. 3. Compression 4. Elastic force that squeezes or pushes matter together 3. Tension 4. An elastic force that stretches or pulls matter

Homework 2 Choice Strategies

Today we will Explain how Newton’s law of motion play a role in forces using Cornell Notes.

1. Newton’s 3 laws of motion.

2. Newton’s 1 st law of motion 3. An object will remain at rest or moving at a constant velocity unless it is acted upon by an unbalanced force 3. Also called the Law of Inertia 4. Inertia is the tendency of an object to resist change in motion and depends on mass

2. Newton’s 2 nd law of motion 3. Acceleration depends on the net force action on the object and on the object’s mass 3. Acceleration = Net force / Mass

2. Newton’s 3 rd law of motion 3. If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. 3. For every action, there is an equal but opposite reaction

3. Action – reaction pairs 4. Jumping off the ground 5. Feet push off the ground = action 5. Ground pushes back with equal force = reaction 4. Others???

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2. Momentum 3. Momentum = mass x velocity 3. SI units are kg x m/s 3. Has a direction and magnitude 3. More momentum = harder to change the velocity

2. Conservation of Momentum 3. Total momentum of any group of objects remains the same, or is conserved, unless outside forces act on the objects. 3. Can be transferred from one object to another

Practice problems Page 392 #’s 1a, 2, 3, 4 Page 399 #’s 1 -5

Chapter 10 and 11 Review White board review for Bonus Points

Forces can be added together only if they are A.Acting on the same object B.Balanced forces C.Unaffected by gravity D.substantial

Which type of elastic force is present on the strings in a guitar? A. Compression B. Tension C. Friction D. Inertia

True or false Unbalanced forces do not change the object’s motion.

True or False Mass and air resistance affect the gravitational attraction between two objects.

True or False The property of matter that resists a change in motion is called inertia.

Snowshoes enable a person to walk on deep snow because the snowshoes. A.Decrease the person’s weight on the snow B.Increase the area over which the person’s weight is distributed. C.Increase the pressure on the snow. D.Increase the buoyancy of the person.

A barometer is used to measure pressure A.In the atmosphere B.Under water C.In hydraulic systems D.Under a snowshoe

Which of the following is true of the buoyant force? A.It acts in the downward direction B.It acts with the force of gravity C.It acts in the upward direction D.It makes an object feel heavier

Flight occurs because of A.Archimedes’ principle B.Pascal’s principle C.Bernoulli’s principle D.Newton's third law of motion

True or False When the only force acting on a falling object is air resistance, the object is said to be in free fall.

Pascal’s principle helps to explain Hydraulic brakes Buoyancy Momentum Flight

In physical science, a push or a pull is called a(n) A.Force B.Acceleration C.Inertia D.Motion

Completion A(n) __________ is an object that is thrown.

The total momentum of a group of objects is conserved unless A.Outside forces do not act on the objects B.Outside forces act on the objects C.The objects are moving D.There are more than two objects

True or False Newton’s third law of motion states that for every action there is an equal but opposite unbalanced force.

Which of the following examples demonstrates a compression force? A. Plucking a guitar string B. Pulling a wagon C. Squeezing a sponge D. Dropping an apple

Completion What are the units for momentum?

True or false Friction depends on the types of surfaces involved and how hard the surfaces push together.

Completion What is the formula for momentum?

How can you increase the momentum of an object? A.By decreasing its velocity B.By increasing its mass C.By increasing its friction D.By decreasing its acceleration

True or false According to Newton’s second law of motion, weight depends on an objects mass and the net force acting on the object.

Completion The overall force on a object after all the forces are added together is called the ___________ force.

Completion Unbalanced forces acting on an object produce a change in the object’s _________.

Completion Wet pavement is more slippery than dry pavement because the force needed to overcome ___________ friction is less than the force needed to overcome sliding friction.

Completion The force of gravity between you and Earth is greater than the force of gravity between you and a car because Earth has more ______ than the car.

Completion The downward force acting on an object in free fall is the force of _____________.

Completion The metric unit that is most often used to describe weight is the ____________.

Completion A person traveling in a car that stops suddenly keeps moving forward due to __________.

Completion According to Newton’s third law of motion, the strength of a reaction force is _________ the strength of the action force.

Completion Friction acts in a direction ___________ to an objects direction of motion.

What happens when two forces act in the same direction? A.They cancel each other out B.The stronger one prevails C.They add together D.Their sum divided by two is the total force

Completion The momentum of an object is in the same _________ as its velocity.

How does the momentum of a 4 kg bowling ball rolling at 3 m/s compare to the momentum of a 6 kg bowling ball rolling at 2 m/s? A.The bowling balls have equal momentum. B.The 4 kg bowling ball has more momentum C.The 6 kg bowling ball has more momentum D.There is not enough information to compare the two bowling balls.

Completion As the distance between two objects decreases, the gravitational force between them ________________.

White Board Review On your white board, answer the following questions.

The combination or addition of all the forces is called a _________________________.

A force that two surfaces exert on each other when they rub against each other is called ____________.

Pressure can be measure in units of A.Newtons B.Newtons per square meter C.Newtons per centimeter D.Newtons per cubic centimeter

What are the four types of friction?

What is an object that is thrown called?

This is the SI unit for force.

Mass x Velocity =

Equal forces acting on one object in opposite directions are called _____________.

What is the definition of force?

What is the definition for unbalanced forces?

Give an example of static friction?

The pressure resulting from a force of 50N exerted over an area of 5 square meters is ______________ Pa.

Pressure ____________ as the area over which a force is distributed increase.

The unit of pressure is called the ____________.

Water pressure ___________ with depth.

A substance whose shape can easily change is a A.Solid B.Powder C.Fluid D.Metal

A material that can easily flow is called a A.Fluid B.Solid C.Buoyant force D.Hydraulic material

Air pressure decreases as A.Velocity increases B.Elevation increases C.Acceleration decreases D.Gravity increases

If an object floats, the volume of displaced water is equal to the volume of A.The entire object B.The portion of the object that is above water C.The portion of the object that is submerged D.Exactly half of the object

When water fills a submarine’s flotation tanks, the overall density of the submarine A.Decreases B.Stays the same C.Increases D.Reduces the buoyant force

What is the formula for density?

One application of Pascal’s principle is A.A hydraulic car lift B.The flight of an airplane C.A speedboat’s bottom slapping against the waves D.The buoyancy shown by ducks and other waterfowl.

What scientific rule describes why water squirts from a plastic bottle when it is squeezed? A.Bernoulli’s principle B.Archimedes’ principle C.Pascal’s principle D.Newton’s first law of motion