April 26, 2018 Mental Math…be ready. You need:

April 26, 2018 Mental Math…be ready. You need:
Clean paper (2) / pencil Simple machines – lab and foldable Warm Up: Mental Math…be ready. I CAN: define the different types of simple machines, where and why they might be used.

Today’s agenda Mental Math Reminders/calendar
Review simple machines lab. Notes – simple machines and Newton.

April 2018 Cougar Mountain! HR 12:10 QUIZ 1 2 No School 3 4 5 6 7 8 14
Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1 Easter 2 No School 3 4 5 6 7 8 9 F/M – review, metrics 10 F/M- KE vs. PE Ramp and marble lab 11 F/M- Bal/un forces Rope, shoes, magnet 12 F/M- Friction, mass, gravity *challenge, quiz 13 F/M- Motion and graphing Story analysis, create the graph. 14 15 16 F/M – Graph review Benchmark 17 F/M/E 18 F/M/E Graphs 19 F/M/E Force/friction 20 F/M/E 21 22 23 Forces and energy Work and Simple machines 24 Work and simple machines QUIZ 25 Mech.adv. HR 12:10 26 Mech. Adv. 27 Mech. Adv Cougar Mountain! 28 29 30 Magnets

Swagrrr EOG testing May 2018 1 2 3 4 Review Test Assess 5 6 7 8 9 10
Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1 Forces and energy Magnets / eclectricity 2 Electricity 3 Catch up 4 Review Test Assess 5 6 7 Atmosphere 8 9 10 11 12 13 Mother’s Day 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 No School Memorial Day 29 30 31 Swagrrr EOG testing

June 2018 EOG testing Busch Gardens NCFE testing 1 2 3 4 5 6 7
Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1 Atmosphere 2 3 4 5 6 7 8 Last day (due to snow) 9 EOG testing Busch Gardens NCFE testing

FORCES Forces may WORK TOGETHER or OPPOSE each other.
When 2 or more forces act on an object, the forces combine to form a net force. Forces may WORK TOGETHER or OPPOSE each other.

MEASURING FORCE The strength of a force is measured in NEWTONS.
The symbol is (N). We use a SPRING SCALE to measure force.

Review of Friction Forces

Review - What is Friction?
Friction is a force that two surfaces exert on each other when they rub against each other. The direction of the friction force is always OPPOSITE to the direction of the motion. It SLOWS down moving objects! Direction of Motion Friction Force

& AIR RESISTANCE The physics of falling
GRAVITY & AIR RESISTANCE The physics of falling

The Force of Gravity Gravity is the force that pulls all objects down to the earth. Rain falls from the sky down to earth… If you drop a book, it falls to the ground… If you trip, you’ll fall down…

Universal Gravitation
Because the Earth is by far, the largest and closest object around, it has the greatest force of attraction... So, no matter where you are on earth, all things fall to the ground due to gravity…

What is “free fall”? When gravity is the ONLY force acting on an object, it is in free fall. In that case, gravity is an UNBALANCED FORCE which causes the object to accelerate.

Acceleration due to Gravity
Calculate the acceleration of an object in free fall. A = Final speed – initial speed time A = 50 m/s – 0 m/s 5 s Acceleration = 10 m/s2

Objects in Free Fall Do all objects fall at the same rate?
ALL objects in free fall travel at the same rate, regardless of mass! In free fall, heavy objects and light objects fall at the same rate!

Gravity Review Gravity is the force that pulls all objects down to the earth. When gravity is the ONLY force acting, ALL objects accelerate at a rate of 10 m/s2. Mass doesn’t matter – in free fall, heavy objects and light objects fall at the same rate!

Air Resistance Review Some objects take longer to fall – they are slowed down by FRICTION with the air called AIR RESISTANCE. The larger the surface area, the greater the force of air resistance pushing up. Without air resistance, all objects would fall at the same rate…

Draw a free body diagram of the sky diver and label ALL the forces.
Gravity = 1000 N Air Resistance = 800 N What is the net force? Air Resistance = 800 N Net Force = 200 N Gravity = 1000 N

Simple Machines (Making work easier…phew!)

Simple Machines Foldable
8 Simple Machine Notes 7 Lever 6 Pulley 5 Wheel & Axle 4 Wedge 3 Screw 2 Inclined Plane 1 Title Tab Simple Machines By John Smith Line up your papers about 1-2 cm apart Fold the papers over. Number and title each flap

Simple Machines Foldable
8 Simple Machine Notes 7 Lever 6 Pulley 5 Wheel & Axle 4 Wedge 3 Screw 2 Inclined Plane Draw & Describe: A sloped surface connecting a lower level to a higher level. Examples: A boat ramp, wheelchair ramp,propeller, ladder/stairs Simple Machines Foldable On each tab, draw and describe that type of simple machine. Then give 2-3 examples.

What are MACHINES? Most people think of complex, technical, or electronic gadgets with motors…, but machines can be much SIMPLER. A machine is any device that lets you do WORK in an EASIER or BETTER way. Basically: Simple machines make work EASIER.

How do machines do work? Machines make work easier by changing 3 things about the FORCE you exert to do work: AMOUNT OF FORCE you exert DISTANCE over which you exert force DIRECTION in which you exert force

What are SIMPLE MACHINES?
There are only 6 basic simple machines that make work easier: Inclined Plane Wedge Screw Lever Wheel & Axle Pulley

COMPOUND MACHINES Compound Machines – are made of combinations of two or more simple machines. For example, a simple can opener is a combination of 3 simple machines: Lever Wheel & axle Wedge

WORK & SIMPLE MACHINES Simple machines DON’T change the amount of WORK done! (They change the size, distance or direction of your FORCE!) WORK IN = WORK OUT* (*usually machines lose a bit of work due to FRICTION…)

INCLINED PLANE An inclined plane is a flat, sloped surface. It connects a lower level to a higher level. You use less force over a longer distance to raise a load to a higher level. Input Force Output Force

INCLINED PLANE: Examples
Ramps (Boat ramps, wheelchair ramps) Propeller Ladders/Stairs

SCREW A screw has a “thread” or “groove” wrapped around a central cylinder. While turning, it converts a twisting force into a forward or backward force. Input Force Output Force

SCREW: Examples & Uses Screws can holds things together or lift materials. Screws Screw top lids for jars/bottles Light bulb Swivel stools/chairs

WEDGE A wedge has slanting slides that meet at an edge – it splits material apart. It changes force in one direction into a splitting force that acts at right angles to the blade. Input Force Output Force

WEDGE: Examples & Uses Ax, Knife, etc. Zippers
Used in all cutting machines (to split materials apart)

WHEEL & AXLE The wheel is locked to the central axle – when one turns, so does the other one. A short powerful force at the axle, will move the wheel’s edge a long distance. A long motion at edge of wheel, moves the axle with great force. Output Force Input Force Output Force Input Force

WHEEL & AXLE: Examples & Uses
Screwdriver Windmill Cars/Bicycles Rolling Pin Door Knob Fan

PULLEY A pulley is a grooved wheel with a rope, used to raise/lower/move a load. Pulley systems change the direction and/or decrease the input force so you can move heavier loads. Output Force Input Force Output Force Input Force

PULLEY: Examples & Uses
Cranes Raising a flag on a pole Window Blinds Raising a sail on a boat Clothesline

LEVER A lever is a bar that pivots or rotates on a point (called a fulcrum). Levers may change the size, distance or direction of the force.

LEVERS: Examples & Uses
First Class Levers: Scissors, See-saws, Pliers Second Class Levers: Staplers, Nutcrackers, Wheelbarrows Third Class Levers Shovels, baseball bats, tweezers

Machines make work easier by changing 3 things about the FORCE:
The amount of force The distance of the force The direction of the force

The amount of force (eg. A ramp lets you lift a heavy object with LESS force)

The distance of the force (eg. A baseball bat lets you move your arms a short distance, but move the end of the bat a large distance).

The direction of the force (eg. The pulley on a set of window blinds lets you move the blinds UP with a DOWNWARD pull.

How do machines make work easier?
In your science notebook, write the following questions: When you add pulleys to a system what happens to the force you need to do work? How can we change a lever to make it easier to lift a heavy weight?

What is the mechanical advantage of a machine?
A machine’s mechanical advantage is the number of times a machine increases a force exerted on it. Mechanical = Output Force Advantage Input Force

What is the mechanical advantage of a machine?
You exert 10 N of force on a can opener. The can opener exerts 30 N of force on the can. What is the mechanical advantage? Mechanical = Output Force = 30 N Advantage Input Force N Mechanical Advantage = 3

What is the efficiency of a machine?
The EFFICIENCY compares: the work you put IN to the work the machine puts OUT. An IDEAL machine is 100% efficient. INPUT WORK = OUTPUT WORK In the real world, some input work is always lost due to FRICTION between the moving parts of the machine.

EFFICIENCY = Output Work x 100% Input Work You mow the lawn with a rusty lawn mower. You do 50,000 J of work on the lawn mower but only 25,000 J go to cutting the lawn. What is the efficiency of the lawn mower?

You mow the lawn with a rusty lawn mower. You do 50,000 J of work on the lawn mower but only 25,000 J go to cutting the lawn. What is the efficiency of the lawn mower? EFFICIENCY = Output Work x 100% Input Work Efficiency = 25,000 J x 100% 50,000 J Efficiency = 50%

Try the rest of the practice problems on your own…
Mechanical = Output Force Advantage Input Force EFFICIENCY = Output Work x 100% Input Work

Making a foldable: Newton’s Laws of
Making a foldable: Newton’s Laws of Motion On the inside, include the following info for each law: 1) What does the law say? 2) What’s an example of a situation that shows the law in action. 3) Draw a picture that shows the law in action. NEWTON’S LAWS Newton’s First Law of Motion Newton’s Second Law of Motion Newton’s Third Law of Motion

THE LAW OF Newton’s 1st Law INERTIA

Newton’s 1st Law of Motion
After the ball is kicked, what forces are acting on it while it rolls? What if we could remove those forces? What would happen then if we kicked the ball? GRAVITY Friction

Newton’s 1st law of motion states: An object at rest will remain at rest, -and- an object moving at a constant velocity will continue moving at a constant velocity, -UNLESS- it is acted upon by an unbalanced force.

BASICALLY… Objects resist any change to their motion! This resistance is called INERTIA. Which one would be easier to push? or… That’s because larger objects have more inertia (more resistance to a change in their motion)!

Unfortunately, your bed really doesn’t make itself… And dirty clothes won’t pick themselves up off the floor! That’s because things at rest will stay at rest until an unbalanced force (like your arms lifting the sheets) acts on them. Make your bed! Do the laundry!

What would happen to the things inside the car if the car hit a wall? That’s because things moving at a constant velocity will stay at a constant velocity unless acted upon by an unbalanced force. The car was acted upon by an outside force – the force of the wall hitting the car. The person inside the car wasn’t hit by the force of the wall, so he kept moving at the same speed and in the same direction. Inside a moving vehicle, everything is moving at the same velocity – your body, the objects in the car, and the car itself.

Explain this animation: The truck is stopped by the force of the impact with the car, but the ladder continues to move at its original speed and in its original direction because of inertia.

Newton’s Laws of Motion Foldable 1) Label your foldable like the one shown on the right. 2) Cut along the 2 dotted lines to make flaps. 3) On the inside, write down what the law states. 4) Write down an example of a situation that shows the law in action. NEWTON’S LAWS Newton’s First Law of Motion Newton’s Second Law of Motion Newton’s Third Law of Motion

THE LAW OF Newton’s 2nd Law Acceleration

Newton’s 2nd Law of Motion
Newton’s 2nd law of motion describes how UNBALANCED FORCES and MASS affect the ACCELERATION of an object.

So, how do unbalanced forces affect an object’s motion?
How does a batter’s swing affect the acceleration of a baseball? Homerun Hit Sacrifice Bunt

So, how do unbalanced forces affect an object’s motion?
The harder you hit, the faster it goes! The greater the force, the greater the acceleration… Homerun Hit Sacrifice Bunt

So, how does mass affect an object’s motion?
Which shopping cart would move faster with a single push? Empty Cart Full Cart

So, how does mass affect an object’s motion?
The fuller the cart, the slower it goes! The more mass, the less acceleration… Empty Cart Full Cart

It states: ACCELERATION depends on the object’s MASS, and the net FORCE acting on the object. We can also write it mathematically: Force = Mass x Acceleration

Newton’s 2nd Law Force = Mass x Acceleration M F A
If you want less acceleration with the same force, you must increase the mass. If you lower the mass but keep force the same, acceleration will increase. M F A If you raise the mass but keep force the same, acceleration will decrease. If you want more acceleration with the same force, you must decrease the mass.

Newton’s 2nd Law Force = Mass x Acceleration
If you want less acceleration with the same mass, you must decrease the force. If you want more acceleration with the same mass, you must increase the force.

Newton’s 2nd Law Force = Mass x Acceleration
If you lower the mass but want the same acceleration, you must decrease the force. If you raise the mass but want the same acceleration, you must increase the force.

Force = Mass x Acceleration Mr. Sawyer’s car ran out of gas. How much force does Mr. Sawyer need to push his 750kg car at an acceleration of 1 m/s2? F = m x a F = 750 kg x 1 m/s2 F = 750 N right 750 kg 1 m/s2

Try one on your own… Ms. Litwak’s van runs out of gas. How much force does she need to push the 2000kg van at an acceleration of 0.5 m/s2? 0.5 m/s2 F = m x a F = 2000 kg x 0.5 m/s2 F = 1000 N right

Speed, Distance & Time We can also write the formula like this: Acceleration = Force Mass Mass = Force Acceleration Force = Mass x Acceleration m F a

Find the golf ball’s acceleration. The putter hits the 0.05 kg golfball with a force of 1 N. The driver hits the 0.05 kg golfball with a force of 8 N.

Use Newton’s 2nd law of motion to explain in words the difference in the motion of the golf balls.

Newton’s Laws of Motion Foldable 1) Label your foldable like the one shown on the right. 2) Cut along the 2 dotted lines to make flaps. 3) On the inside, write down what the law states. 4) Write down an example of a situation that shows the law in action. NEWTON’S LAWS Newton’s First Law of Motion Newton’s Second Law of Motion Newton’s Third Law of Motion

THE LAW OF Newton’s 3rd Law Interaction

Which forces are acting to get this guy up in the air?
His feet push DOWN on the ground. But wait… His downward push can’t be causing his upward motion.

Which forces are acting to get this guy up in the air?
His feet push DOWN on the ground. The ground pushes UP on the man. There must be a force pushing UP! The force of the ground pushes him UP!

Newton’s 3rd Law of Motion
Newton’s 3rd law says that: For every action force, there is an equal and opposite reaction force. ALL forces act in PAIRS! Action Force: Man’s feet push DOWN on the ground. Reaction Force: Ground pushes UP on the man.

Let’s Demonstrate… Stand up and face a partner with your palms touching. Push on your partners hands. Don’t move your feet. The first partner to step back loses… How can Newton’s third law explain what happens?

Explain this animation using Newton’s third law.

The man’s foot exerts a backward push on the boat (action force), while the boat exerts a forward push on the man (reaction force). A PAIR OF FORCES: EQUAL FORCES, BUT IN OPPOSITE DIRECTIONS

Let’s Demonstrate… Two people (the same size) in rolling chairs face each other with their feet touching. Only 1 student pushes. What will happen? How can Newton’s third law explain what happens?

Identify the force pairs in each situation
A person fires a rifle. Action Force – gun pushes the bullet out at high speed. Reaction Force – the bullet pushes back on the gun (recoil).

A space shuttle lifts off. Action Force – engine pushes gases down & out. Reaction Force – the gases push the rocket up. *This upward force must be stronger than gravity pulling down on the rocket!

A person stands still. Action Force – gravity pulls the person down to the floor. Reaction Force – the floor pushes up on the person. *You don’t need MOTION for force pairs. They are everywhere!

If forces are equal and in opposite directions, why don’t they cancel out (and balance)?
Forces only cancel if they act on the same object. (Think about a tug of war – all forces act on the rope). These forces are acting on different objects! These forces are acting on different objects! Action Force – Rocket engine pushing on gases. Reaction Force – Gases push on the rocket.

Think about it . . . Why does it hurt so much when you stub your toe?
When your toe exerts a force on a table, the table exerts an equal force back on your toe. The harder you hit your toe against it, the more force the the table exerts back on your toe (and the more your toe hurts).

What is Momentum? Momentum is a measure of how much motion object has.
It is affected by mass and velocity. The heavier an object is, the more momentum it has. It’s easier to stop soccer ball coming towards you at 20 m/s than a car coming at 20 m/s. It’s easier to stop car travelling at 1 km/h than a car travelling 60 km/h!

Conservation of Momentum
When objects collide, their total momentum is conserved (stays the same), unless outside forces act. The total amount of motion coming into a collision will also come out of the collision.

Place 4 coins in a row, touching each other.
Place the 5th coin about 2 inches away from the end of the row, keeping it in line. Lightly flick your finger forward, propelling the single coin against the others. What do you observe? Try it again, flicking 2 coins into a row of 3 coins. What do you observe?

Momentum = mass x velocity
Momentum can be calculated using this formula: Momentum = mass x velocity A golf ball with a mass of 0.05 kg travels at 16 m/s. A baseball with a mass of 0.15 kg travels at 7 m/s. Which ball has the greater momentum? Golf ball’s momentum = 0.05 kg x 16 m/s Baseball’s momentum = 0.15 kg x 7 m/s = 0.8 kg m/s = 1.05 kg m/s

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