Physics Unit: Force & Motion What is physical science?

A. Physical science is a field of science that studies matter and energy. B. Physical science has 2 main branches:

1. PHYSICS: the study of how matter and energy interact •  robotics, nuclear energy, solar

panels 2. CHEMISTRY: the study of the

structure, makeup, and changes of matter •  chemicals, acids & bases,

medicines

What is energy? A.  ENERGY: the ability to do work or

make something happen B.  All forms of energy fall under two

categories: 1.  POTENTIAL ENERGY: stored

energy that could make something happen a.  Chemical Energy b.  Nuclear Energy c.  Stored Mechanical Energy d.  Gravitational Energy

2.  KINETIC ENERGY: used energy that is making something happen a.  Radiant Energy b.  Thermal Energy c.  Motion d.  Electrical Energy e.  Sound

What are the different forms of energy?

A.  There are many different forms of energy to make things happen.

B.  Below are 6 of the major forms: 1.  MECHANICAL ENERGY: the

energy in moving objects 2.  ELECTRICAL ENERGY: energy

from the flow of electrons 3.  ELECTROMAGNETIC ENERGY:

energy in the form electrical and magnetic waves that can travel through space

4.  HEAT ENERGY: thermal energy that comes from moving particles of matter (friction)

5.  CHEMICAL ENERGY: energy that holds particles of matter together (chemical bonds)

6.  NUCLEAR ENERGY: energy stored in an atom’s nucleus

What happens to energy? A.  Energy is never lost, it only

changes into another kind or form of energy. 1.  Potential becomes kinetic

and vice versa. a. Roller coaster moving

from hill to hill 2.  Chemical energy becomes

electrical energy becomes light energy becomes heat energy a. Battery to electricity to a

lit light bulb that gets hot B.  LAW OF THE CONSERVATION

OF ENERGY: energy can neither be created nor destroyed, only changed in form.

What is a wave? A.  WAVE: a disturbance that transfers

energy from one place to another. 1.  A wave is energy traveling through a

medium like particles of air or water 2.  There are two major forms of waves:

a.  MECHANICAL WAVES: waves that travel through matter

b.  ELECTROMAGNETIC WAVES: waves that can travel through matter or empty space

3.  All waves have 3 features in common: a.  WAVELENGTH: the distance

between one full wave to another b.  FREQUENCY: the number of

complete waves that pass a certain point per second

c.  AMPLITUDE: the height of a transverse wave or the amount of compression of a longitudinal wave

What is a wave? B.  Waves that travel through matter can do it one of two ways:

1.  TRANSVERSE WAVE: waves that move up and down a.  There are two parts to a transverse wave

i.  CREST: the highest point of a wave ii.  TROUGH: the lowest point of a wave

b.  A wavelength is from one crest to another c.  Amplitude is the height of the crest

2.  LONGITUDINAL WAVE: waves that move back and forth a.  There are two parts to a longitudinal wave

i.  COMPRESSION: where the particles are close together ii.  RAREFACTION: where particles are far apart

b.  A wavelength is from one compression to another c.  Amplitude is the tightness or looseness of the compression

What is Light? A.  LIGHT: a form of electromagnetic

energy made up of streams of photons. 1.  PHOTON: a very small bundle of

energy 2.  Light behaves like a transverse

wave that can travel through matter or empty space

3.  Light waves have four properties: a.  The speed of light is 300,000

km/s in space b.  The wavelength is measured

from crest to crest c.  Frequency is measured by the

number of light waves that pass a certain point each second

d.  Amplitude is the height of the crest with bright light having taller crests and dim light having shorter crests

What is Light? B.  When light interacts with matter or objects made of matter, the light

will behave in different ways 1.  Some objects can allow light to be transmitted, absorbed or reflected.

a.  TRANSMISSION: light passes through an object b.  ABSORBTION: light is absorbed into an object c.  REFLECTION: light bounces off an object

2.  Some objects can be categorized as luminous or illuminated. a.  LUMINOUS OBJECT: objects that give off light b.  ILLUMINATED OBJECTS: objects that reflect light

i.  OPAQUE: objects that block light ii.  TRANSPARENT: objects that allow light to pass through iii.  TRANSLUCENT: objects that allow some light to pass through

What is Light? 3.  Some matter can cause light to change the direction it is traveling as

its transmitted a.  REFRACTION: the bending of light when it passes from one

transparent material to another b.  LENS: a transparent material that refracts light inward or outward

4.  Some matter has surfaces that allow a type of reflection that causes an image 1.  Mirrors are examples of surfaces that reflect light causing an

image

What is mechanical energy? A.  MECHANICAL ENERGY: the energy

an object has that causes it to move B.  Mechanical energy can come in one of

two ways: 1.  STORED MECHANICAL

ENERGY: potential mechanical energy that could cause an object to move

2.  MOTION: kinetic mechanical energy that causes an object to move

C. A force acting on an object is required for mechanical energy

What is a force? A.  FORCE: a push or pull exerted on an object B.  To describe a force, you must know a force’s size and direction C.  Size and direction can cause one of two situations:

1.  BALANCED FORCES: forces on an object equal in size but opposite in direction

2.  UNBALANCED FORCES: forces on an object that are no longer balanced, causing a change in the motion of an object

How is a force depicted, described, and measured? A.  A force is often depicted with the use of arrows that come in various

sizes. 1.  Arrows show direction 2.  Different sized arrows show how strong the force is

B.  Forces are often measured using instruments: 1. A spring scale is often used to measure a force, they measure a force using newtons 2. NEWTON: a standard unit of force depicted as an N

3 N 3 N 3 N

1 N

8 N

3 N

What is motion? A.  Mo%oniskine%cmechanicalenergythat

causesanobjecttomoveB.  Mo%onisobservedwhenanobject

changesitsposi%onorloca%onascomparedtosomethingelsethathasafixedposi%on1.  Weknowanobjectisinmo%onwhen

itchangesposi%oninanenvironmentwhereotherthingsaren’tmovingwithit.

2.  Cardrivesdownthestreetandweno%ceitmoveawaybecauseweandotherthingsaren’tmovingwithit.

How is motion described? A.  Motion can be described in terms of speed and direction:

1.  VELOCITY: the speed and direction of a moving object a.  Speed is a measurement of how fast an object is moving

i.  Distance in meters (m) ii.  Time in seconds (s)

b.  Direction must be figured out using a compass to determine N, S, E, W, NE, NW, SE, SW, etc.

C. When an object changes speed or direction, it is accelerating 1.  ACCELERATION: a change in an object’s velocity 2.  Acceleration occurs when an object:

a.  Slows down or moves faster b.  Changes the direction it is moving

B. Velocity can be written as a formula: 1. Distance ÷ Time & Direction = Velocity 2. Velocity is written in meters per second m/s

a. m ÷s&direc%on=m/s&direc%on

What is Work? A.  WORK: force exerted on an object that moves it over a measurable

distance 1.  Two things must be measured to determine work:

a.  Force in Newtons (N) b.  Distance in meters (m)

2.  If an object does not move, no work is accomplished. B.  Energy can be defined as the ability to do work.

1.  For work to be done, a force must make an object move. 2.  If a force is exerted, but there is no movement then no work has

been accomplished.

C.  Work can be written as a formula: 1.  Force x Distance = Work 2.  Work is written in Joules (J)

a.  a. JOULE: a unit of work equal to a force of 1 N that moves an object 1 m.

b.  N x m = J

What is Power? A.  POWER: the amount of work done per unit of time

1.  Power is the rate at which work is done 2.  To determine power, two things must be measured:

a.  Work in Joules (J) b.  Time in seconds (s)

B.  There is a formula for power: 1.  Work ÷ Time = Power 2.  WATT: a unit of power equal to 1 Joule of work per second

What is Momentum? A.  MOMENTUM: a property of all moving objects where an object

with greater mass and/or velocity will have greater mechanical energy

B.  mass x velocity = momentum (g x m/s = g m/s) 1.  If two objects with the same mass are moving, the one with

greater velocity has more mechanical energy 2.  If two objects are moving with the same velocity, the one

with greater mass has more mechanical energy. C.  THE LAW OF THE CONSERVATION OF MOMENTUM:

momentum of an object can be transferred to other objects but can not be lost

Which major forces affect the motion of objects?

A. Gravity is one of the major forces acting on objects 1.  GRAVITY: a force of attraction

between all objects in the universe

2.  An object has more pull if its made of more matter

3.  An object has more pull if its closer to another object

B. On Earth, objects are pulled to the center of the planet by the dense mass of the planet’s core

Which major forces affect the motion of objects?

C. Friction is another major force moving objects must contend with: 1.  FRICTION: a force that pushes

back on a moving object 2.  This force often occurs when an

object moves over or through another type of matter

D. There are different types of friction: 1.  STATIC FRICTION: friction an

object must overcome to start moving

2.  AIR RESISTANCE: friction an object experiences when moving through air

3.  ROLLING FRICTION: friction between a surface and a circular object

Which major forces affect the motion of objects?

E. Friction can aid in motion and slow or prevent motion: 1.  The wheels of a bike must push against the road to

begin moving (friction) 2.  The tread on shoes must push against the floor to walk

(friction) 3.  A braking car must move against a surface to stop

(friction) 4.  A heavy box won’t move across a course surface

(friction) F. The level of friction on an object can be overcome or altered

to move an object 1.  A push or pull stronger than the force of friction will allow

an object to move 2.  Allowing an object to roll reduces the friction on that object 3.  LUBRICANT: materials that reduce friction; like oil, ice,

lotions, smooth surfaces, etc.

What is a Simple Machine? A.  MACHINE: a device that makes work easier

1.  A machine can make work easier in three ways: a.  Reducing the size of the force b.  Changing the direction of the force c.  Changing the speed of the force

2.  Most machines are a combination of two or more simple machines: a.  LEVER b.  INCLINED PLANE c.  WHEEL & AXLE d.  PULLEY e.  SCREW f.  WEDGE

What is a Simple Machine? B.Work is a force exerted on an object allowing the

object to move a distance 1.  When working with a machine there are two primary

forces involved: a.  EFFORT FORCE: the force applied to the machine to

accomplish work b.  RESISTANCE FORCE: the force of the object that

opposes the effort force

What is a Simple Machine? C. Most machines make work easier by maximizing the effort force

you apply to the machine. 1.  MECHANICAL ADVANTAGE (MA): the number of times a

machine multiplies the effort force a.  Mechanical advantage determined using a formula:

•  Resistance force ÷ Effort force = MA •  RF 25 N ÷ EF 5 N = 5 MA

b.  The greater the MA the more the machine is maximizing your effort force.

How do Levers Work? A.  LEVER: a bar or plane that is free to pivot or turn around a fixed

point 1.  Three major parts of a lever:

a.  FULCRUM: the fixed point a lever pivots or turns around b.  EFFORT ARM: the part of the bar from the effort force to

the fulcrum c.  RESISTANCE ARM: the part of the bar from the fulcrum

to the resistance force

How do Levers Work? B.Aleverdoestwothingstomake

workeasier:1.  Reducesthesizeoftheeffort

forcerequired2.  Changesthedirec%onofthe

forceC.Therearethreetypesorclassesof

leversbasedontheposi%onofthefulcrum,EF,andRF:1.  Firstclasslever:thefulcrumis

betweentheEF&RF(crowbar)2.  Secondclasslever:theRFis

betweenthefulcrum&EF(wheelbarrow)

3.  Thirdclasslever:theEFisbetweenthefulcrum&RF(shovel)

How do Wheel & Axles Work? A.   WHEEL&AXLE:acircularobjectthatturnsaroundafix

pointorrod1.  Awheelandaxlereducestheamountoffric%onbetween

theresistanceandthesurfaceitmovesover.2.  Thelongertheradius(fromaxletoedgeofwheel)thefurther

thedistancethewheelwillmove.

How do Wheel and Axles Work? B.Wheel&axlesarepartsofothersimplemachines:

1.  Pulleysareawheelandaxlewitharopewrappedaroundit2.  Gearsarespecialwheelswithteethabletobiteandturneach

other.

How Do Inclined Planes Work? A.   INCLINEDPLANES:aslantedsurfaceorramp

1.  AninclinedplanemakesworkeasierbychangingtheangleyouhavetoexertaforcetoliWanobject.

2.  Thelessertheangleofaninclinedplane,lessforceneedstobeexerted.

How Do Inclined Planes Work? B.Inclinedplanesarepartsofothersimplemachines:

1.  Awedgeistwoplanesbacktoback2.  Ascrewisaninclinedplanedwrappedaroundacylinder.

What are Newton’s Laws of Motion? A.  SirIsaacNewtoniscreditedasthefatherofclassic

mechanics.Hedevelopedthreelawsofmo%ons%llusedtoday:1.  FirstLawofMo%on:INERTIA:anobjectatrestorin

mo6onwillremainatrestorinmo6onataconstantspeedonastraightpathun6lacteduponbyanunbalancedforce

2.  SecondLawofMo%on:theunbalancedforceac6ngonanobjectisequaltotheobject’smass6mesitsaccelera6on(aforcewillcauseagreaterchangeinvelocityonanobjectwithlessmassthanonewithgreatermass)

3.  ThirdLawofMo%on:foreveryac6onforce,thereisanequalandoppositereac6onforce