You need Clean paper 2 pencil Newtons Foldable

You need: -Clean paper (2) / pencil -Newton’s Foldable Nov. 28, 2018 Warm Up: What does Newton’s 1 st law say? How is that like 7 th graders? I CAN: identify the basic laws of motion (Newton’s)

November 2018 Force/Motion Friction / Gravity Force/Motion Newton’s Laws Force/Motion Simple Machines Force/Motion

December 2018 TEST!! Force/Motion Weather Weather Weather

Types of Friction • Static Friction opposes the motion of an object that is at rest • To make the object move, you have to exert a force larger than the force of static friction. Direction of Intended Movement Static Friction Force

Types of Friction • Sliding friction occurs when two solids slide over each other. • Sliding friction makes car brakes work and stops athletes from slipping. Direction of Slide Sliding Friction Force

Types of Friction • Rolling friction occurs when an object rolls across a surface. • Rolling friction is easier to overcome than sliding friction for the same materials. Direction of Motion Friction Force

Types of Friction • Fluid friction occurs when a solid object moves through a liquid or gas. • Air resistance is a type of fluid friction. Direction of Motion Friction Force

GRAVITY & AIR RESISTANCE The physics of falling

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/s 2. • 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…

st Newton’s 1 Law

Newton’s st 1 Law of Motion • Newton’s 1 st law of motion states: An object at rest will remain at rest, -andan object moving at a constant velocity will continue moving at a constant velocity, -UNLESSit is acted upon by an unbalanced force.

Newton’s st 1 Law of Motion BASICALLY… Objects resist any change to their motion! That’s because larger objects have more inertia (more resistance a change in This resistance is calledto INERTIA. their motion)! Which one would be easier to push? or…

Newton’s st 1 Law of Motion • The car was acted upon outside force What would happen to by theanthings inside • Inside aifmoving vehicle, everything –the thecar force of the wall the car. is the car hitting a wall? at the same velocity – your body, • • moving The person inside the car wasn’t hit by the That’s because things moving at a the objects in the car, and moving the caratitself. force of the wall, so he kept the constant velocity will stay at a constant same speed and acted in the same velocity unless upon direction. by an unbalanced force.

Newton’s st 1 Law of Motion • 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 Newton’s First Law of Motion 1) Label your foldable like the one shown on the right. 2) Cut along the 2 dotted lines to make flaps. Newton’s Secon d Law of Motion 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 Third Law of Motion N E W T O N ’S L A W S

nd Newton’s 2 Law

Newton’s 2 nd Law of Motion • Newton’s 2 nd 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? Sacrifice Bunt Homerun Hit

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… Sacrifice Bunt Homerun Hit

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

Newton’s 2 nd Law of Motion 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 nd 2 Law of Motion Force = Mass x Acceleration Mr. Sawyer’s car ran out of gas. How much force does Mr. Sawyer need to push his 750 kg car at an acceleration of 1 m/s 2? F=mxa 750 kg 1 m/s 2 F = 750 kg x 1 m/s 2 F = 750 N right

Try one on your own… Ms. Litwak’s van runs out of gas. How much force does she need to push the 2000 kg van at an acceleration of 0. 5 m/s 2? 0. 5 m/s 2 F=mxa F = 2000 kg x 0. 5 m/s 2 F = 1000 N right

nd Speed, Distance Time. Motion Newton’s 2 Law& of We can also write the formula like this: Acceleration = Force Mass F m a Mass = Force Acceleration Force = Mass x Acceleration

Newton’s nd 2 Law of Motion Find the golf ball’s acceleration. a) The putter hits the 0. 05 kg golfball with a force of 1 N. b) The driver hits the 0. 05 kg golfball with a force of 8 N.

Newton’s nd 2 Law of Motion • Use Newton’s 2 nd 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 First Law of Motion Newton’s Secon d Law of Motion Newton’s Third Law of Motion N E W T O N ’S L A W S

rd Newton’s 3 Law

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

Newton’s rd 3 Law of Motion • Explain this animation using Newton’s third law.

Newton’s rd 3 Law of Motion • The man’s. Afoot a backward PAIRexerts OF FORCES: EQUAL push on the boat. FORCES, (action. BUT force), IN exerts OPPOSITE while the boat a forward DIRECTIONS push on the man (reaction force).

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).

Identify the force pairs in each situation • 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!

Identify the force pairs in each situation • 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 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 These forces are acting on act on the same object. different objects! (Think about a tug of war – all forces. Force act on the rope). • Action – Rocket engine pushing on gases. • These forces are acting on different objects! • Reaction Force – Gases push on the rocket.

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.

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 = 0. 8 kg m/s Baseball’s momentum = 0. 15 kg x 7 m/s = 1. 05 kg m/s