 # Physics the study of the relationship between matter and energy.

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Physics the study of the relationship between matter and energy

Motion  A change in position in a certain amount of time  Motion is relative. To know you are moving, you must have a reference point  Distance – how far you traveled

Distance vs. Displacement  The distance between the final position and starting position is displacement  (Ex: hiking on a trail. The trail may be 1 mile long but you may only end up 300 ft from where you started)

Speed Equation  Speed – the distance traveled divided by the time needed to travel that distance  SI Unit is meters per second (m/s)  Speed = distance time D S T

Practice (Make sure you use the proper units)  If it takes you 3 hours to travel 60 miles, what is your speed??  If you are running 3 miles in 30 minutes, what is your speed?

Constant speed vs. Average speed  Constant speed – an object covers equal distances in equal amounts of time  The speed of moving objects is not always constant  Average speed: total distance total time

Graphing Speed

What is happening in the following graph?

Velocity  Velocity: Speed in a given direction You can be going the same speed but two different velocities  Velocity = distance + direction time D TV

Acceleration  The change in velocity divided by the time the change occurs A = Velocity (final) – Velocity (initial) Time  Acceleration is speeding up, slowing down or changing direction

Stop Here!!!

Warm Up 4/8  Tell me something about Force and Motion that begins with each letter RN SE T2 more consonants L1 more vowel

Force  What causes an object to accelerate?  A force is a push or pull exerted on an object  Force is measured in Newtons (kg m/s2)  In order for an object to speed up, slow down or change direction, a force has to act on that object  Inertia is the object’s tendency to resist changing its motion. The more inertia, the harder it is to start moving or slow it down

Total Force  Sometimes, more than one force can act on an object at the same time. Those forces together will affect the object’s motion.  Forces usually act in pairs with one force acting on either side of the object  The resulting force that exists between two is the total force

Unbalanced Forces When a total force acts on an object, they are said to be unbalanced. Unbalanced forces can cause an object to start moving, stop moving, or change direction.

Balanced Forces  Balanced forces exist when the total force is equal to zero.  Balanced forces do not change an object’s motion

Friction and Air Resistance  Friction is the force between two objects in contact that resists motion between two touching surfaces  It is what eventually causes things to slow down and stop  Air Resistance is a form of friction between an object and air molecules

Gravity  Gravity is the pull that all matter exerts on other matter  Gravity is dependent on the mass of an object and the distance between the two objects The greater the mass, the more gravitational pull it will have (i.e.: earth vs. moon) The greater the distance, the less gravitational pull it will have  Mass vs Weight – weight is the amount of gravitational pull on a person. So on the moon, your mass would be the same but weight would be different

Free Fall and Terminal Velocity  When the only force acting on an object is gravity, the object is said to be in free fall  On earth, this is 9.8 m/s 2 - Gravity constant  In the absence of air resistance, all objects on Earth accelerate at the same rate, regardless of their mass.  An object reaches its terminal velocity when the force of gravity is balanced by the force of air resistance

Gravity Demo

Newton’s Laws

Newton’s First Law of Motion  “ An object at rest will remain at rest and an object in motion will maintain its velocity unless it experiences an unbalanced force.”  This is often times called the law of Inertia

Newton’s Second Law of Motion  “The unbalanced force acting on an object equals the object’s mass times its acceleration”  F=ma  Force is measured in Newtons (kg m/s 2 )

Newton’s Third Law  For every action force, there is an equal and opposite reaction force

write the following on your notes on force and motion  Forces always act in PAIRS  EX

 How much time does it take for a snail to crawl 20 feet if he goes 2 feet/hr  Make sure you have turned in your speed problems worksheet!!!

 Get a calculator and begin calculate your speeds for the 4 activities  Remember: Speed = Distance/Time  Round everything to the nearest hundreths (ex. 5.45s)  Make sure and list your units in your answers

 What is the formula for finding speed?  What is the formula for finding distance?  What is the formula for finding time?  Remember 2 nd Law: F=MA

 What is speed?  How do you calculate it?

Warm Up 11/4 Write Q&A  Write an example of something that goes along with each of Newton’s Laws Ex  1st - A car will sit at a stoplight until you press the gas  2nd - It is harder to carry a box of rocks than a box of popcorn  3rd - When birds fly, they push their wings down in order to go up

Warm Up 11/4  List 5 Examples of motion that you see in your everyday activities

Warm Up 11/3  Make a KWL Chart (3 things in each)  Tell me what you KNOW about motion  What you WANT to know about motion  Leave the L blank for now KLW

Warm Up 11/2 Write Q&A  What is Motion?  P.102

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