Physical Science Final

What is SCIENCE?

A step by step process that builds and organizes knowledge in the form of testable explanations and predictions about the universe

What is PHYSICAL SCIENCE?

The study of matter and energy

What is an OBSERVATION?

Something that you can experience with your senses or measure
- Ex. Debi is reading a book mwahahahahahaha

What is an INFERENCE?

A conclusion reached on the basis of evidence and reasoning based on observations
- Ex. Observation: Debi is reading a book
Inference: Debi likes to read

What is the SCIENTIFIC METHOD?

A systematic way of discovering the truth about something

What is a SCIENTIFIC MODEL?

A simplified version of something (phenomena) that can be tested
- Like the Bohr model of an atom!!!!!!!!!!!

What is the METRIC SYSTEM?

The decimal (0.1, 1, 10) measuring system
- Meter, liter, and gram as units of length
- Capacity, and weight as units of scale

What is VOLUME?

The amount of space an object takes up
- Liter, milliliter, or cubic centimeter

➵ Tools
- Graduated cylinder
- Overflow can

What is MASS?

A measure of the amount of matter in an object
- Kilogram or gram

➵ Tools
- Balance

What is WEIGHT?

A measure of the force of gravity on an object (can also be found using a scale)
- FORCE OF GRAVITY ON EARTH: 9.8 N/kg
- Measured in NEWTONS

➵ Formula:
Fw (force of weight) \= M (mass) · G (acceleration due to gravity)
- Ex. How much does a 12 kg box weigh on Earth in Newtons?
Fw: ? Fw \= mg
m \= 12 kg Fw \= 12 kg · 9.8 N/kg
g \= 9.8 N/kg Fw \= 117.6 N (ROUND TO SIG FIGS!!!!)
Fw \= 120 N

What is DISTANCE?

How far something is or has moved
- Meters or centimeters

➵ Tools
- Rulers

What is TIME?

How long some is or takes
- Seconds, minutes, hours

➵ Tools
- Clock lol

What are the metric prefixes from LARGEST TO SMALLEST?

Kilo, Hecto, Deka, Base Unit, Deci, Centi, Milli 1000 100 10 (m, L, g) 0.1 0.01 0.001 King Henry Died Drinking Choco Milk

➵ m = Meters (base unit for LENGTH)

* 1 meter = 39.37 inches
* 100 centimeters (cm) = 1 meter
* 2.5 cm = 1 inch (centimeters are smaller than inches)
* 1000 millimeters (mm) = 1 meter
* 10 mm = 1 cm

➵ L = Liters (base unit for VOLUME)
1000 milliliters = 1 liter

➵ g = Grams (base unit for MASS)
1 gram = 0.001 kilograms
1000 grams = 1 kilogram

How do you convert metric units?

- To convert into a SMALLER unit, move the decimal to the RIGHT or MULTIPLY
- To convert into a LARGER unit, move the decimal to the LEFT or DIVIDE

➵ Ex. 2000 milligrams (smaller) \= ? grams (larger)
According to the chart, move the decimal THREE places to the left to get from MILLIGRAMS to GRAMS
2000 milligrams (smaller) \= 2 grams (larger)
OR
You can DIVIDE by 1000
2000 milligrams/1000 \= 2 grams

➵ Ex. 7 liters (larger) \= ? milliliters (smaller)
According to the chart, move the decimal THREE places to the RIGHT
7 liters (larger) \= 7000 milliliters (smaller)
OR
You can MULTIPLY by 1000
7 liters · 1000 \= 7000 milliliters

What is TOLERANCE?

How perfect (accurate) your measurement needs to be to do the job you want

What is RESOLUTION?

The resolution of a measuring device is related to how much detail it will read
- Distance between tick marks
- What the ruler goes up by

➵ SMALL SPACES \= HIGH RESOLUTION
➵ BIGGER SPACES \= LOW RESOLUTION

What is an INDEPENDENT VARIABLE?

Variable that is being tested
- Changed by the experimenter
- X-AXIS

➵ Ex. Debi is watering plants differently to see how long the plants will get with different water amounts on a window sill
- INDEPENDENT VARIABLE? - Amount of water the plants are getting

What is a DEPENDENT VARIABLE?

Variable that you are measuring
- Shows the effect of changing the independent variable
- Y-AXIS

➵ Ex. Debi is watering plants differently to see how long the plants will get with different water amounts on a window sill
- DEPENDENT VARIABLE? - The height of the plants (being measured from the different amounts of water)

What is a CONTROLLED VARIABLE?

Variable that stays the same in an experiement
- NOT being changed

➵ Ex. Debi is watering plants differently to see how long the plants will get with different water amounts on a window sill
- CONTROLLED VARIABLE? - Type of plant, what the water is being poured out of, amount of sun, Debi (hopefully)

What is a TRIAL?

One run of an experiment

What are SIGNIFICANT DIGITS?

Each of the digits of a number that is used to express it to the required degree of accuracy

Was the number counted? - Yes - Unlimited Sig Figs
∣
No
∣
Does your number have a decimal point?
∣ ∣
Yes No
∣ ∣
Leading Zeros? Ex. 0.043 Trailing Zeros? Ex. 2100
Yes: Don't count them Ex. 43 Yes: Don't count them Ex. 21
No: All digits are significant No: All digits are significant

➵ REMEMBER:
- When ADDING and SUBTRACTING measurements the result has the same number of decimal places as the number with the FEWER number of decimal places

- When MULTIPLYING and DIVIDING measurements the result has the same number of significant figures as the number with the FEWEST number of significant figures

What are counted numbers?

Numbers that can be counted
- Like 25 bottles or 129398 people
- UNLIMITED amount of significant digits

How many variables can be changed in an experiment at a time?

- One
- Uno
- Eins
- Unus

How can you convert 28000 SECONDS into HOURS?

28000 seconds \= ? hours
3600 seconds \= 1 hour
28000/3600 \= 7.777....8
28000 seconds \= about 7.8 hours (or just ~8 hours)

How do you convert 74000 SECONDS into MINUTES?

74000 seconds \= ? minutes
60 seconds \= 1 minute
74000/60 \= 1233.33333....
74000 seconds \= about 1233.34 hours (or just ~1233 hours)

One day, Debi walks along the snowy sidewalk and sees a car not being able to move out of the snow. Debi immediately decides that the large amount of snow is stopping the car from moving. What is this statement BEST described as?

A hypothesis (an educated guess/conclusion)

What is a SCIENTIFIC THEORY?

An explanation for WHY something happens
- Uses LAWS
- Based on a whole lot of evidence generated over time

What is a SCIENTIFIC LAW?

A principle or a way of following something
- Usually a mathematical function

What is PHYSICS?

A branch of science concerned with the nature and properties of matter and energy
➵ Include:
- mechanics
- heat
- light and other radiation
- sound
- electricity
- magnetism
- the structure of atoms.

What is MECHANICS?

The study of the motion of objects

What is MOTION?

A change in position or location in relation to an unmoving object over a certain period of time
- the Y-INTERCEPT shows you where motion starts

➵ The sign positive or negative sign (+,-) of the slope of the line tells you the direction of the motion
- Positive slope (up) \= forward, to the right
- Negative slope (down) \= backward, to the left

What is POSITION?

An object's distance and direction from a reference point

What is an ORIGIN?

The starting location

What is SPEED?

How quickly something is moving
- how far something is traveling in a certain amount of time
- steeper slope \= speedy mcspeedster (flat slop \= slower)

What is VELOCITY?

How quickly something is moving and in which direction
- SPEED WITH DIRECTION!!!!!!!!!!

➵ How do you find VELOCITY?
VELOCITY \= DISTANCE/TIME
or
DISTANCE \= VELOCITY · TIME
or
TIME \= DISTANCE/VELOCITY

➵ Units
cm/sec - centimeters per second
m/sec - meters per second
m/min - meters per minute
km/hr - kilometers per hour

What is AVERAGE SPEED?

The TOTAL DISTANCE divided by the TOTAL TIME
- Basically velocity
- On a graph, the number value of the SLOPE tells you average speed (velocity)

What is INSTANTANEOUS SPEED?

The speed at any given moment
- Measured with a SPEEDOMETER

What is ACCELERATION?

The rate at which velocity changes
- Change in speed and direction
- Any motion you feel is acceleration
- Caused by a FORCE
- FORCE is what gives acceleration a DIRECTION

➵ FORMULA
ACCELERATION \= VELOCITY(finish) - VELOCITY (start)/TIME
(A \= V₂-V₁/t)
- TIME \= (V₂-V₁) ÷ ACCELERATION
- ACCELERATION x TIME + V₁ \= V₂
- V₂ - ACCELERATION x TIME \= V₁
UNIT - M/S^2, CM/S^2, MI/HR/SEC

What does a POSITION versus TIME graph tell you?

➵ Axis
- Y-axis - Position
- X-axis - time

➵ Slope tells you velocity.
- 0 (flat) - stopped
- Positive slope (up) traveling forward
- Negative slope (down) traveling backward

➵ Shape of the line tells you acceleration
- curved steeper \= speeding up
- curved flatter \= slowing down

What does a VELOCITY versus TIME graph tell you?

➵ Axis
- Y-axis - velocity
- X-axis - time

➵ Slope tells you acceleration.
- 0 (flat) constant speed
- Positive slope (up) speeding up
- Negative slope (down) slowing down

➵ Quadrant tells you direction
- Quadrant 1 means traveling in the positive direction (forward)
- Quadrant 4 means traveling the negative direction (backward)

In 5 hours, Debi was biking for a distance of 425 kilometers. What was her average speed?

VELOCITY \= DISTANCE/TIME
? \= 425/5
425/5 \= 85
\= 90 km/hr (rounded to significant figures)

What is FORCE?

Any PUSH or PULL
- Measured in Pounds (lb) or Newtons (N)
- Contact & Non-contact

➵ Fundamental (basic) forces
- Strong
- Weak
- Gravity
- Electromagnetic

What is GRAVITY?

- Represented by Fg or Fw
-EVERYTHING HAS GRAVITY!!
- Goes straight DOWN
- Does NOT require contact

What is APPLIED FORCE?

- Represented by Fa
- A push or pull on an object
- Direction of the push is the direction of the PUSH OR PULL
- Requires contact

What is NORMAL FORCE?

- Represented by Fn
- Ask yourself: Is it on a surface? If yes, it has a normal force (HAS TO BE ON A SURFACE)
- PERPENDICULAR to the surface and going AWAY from the surface
- Requires contact

What is FRICTION?

- Represented by Ff
- Anything that touches something else
- OPPOSITE of the direction of the motion
- Requires contact

What is AIR RESISTANCE?

- Represented by Fair
- Ask yourself: Is it moving? If yes, it has air resistance
- ANYTHING MOVING (Big surface \= more air resistance)
- OPPOSITE of the direction of motion
- Requires contact

What is TENSION?

- Represented by FT
- Pulled or supported by a ROPE
- Requires Contact

What is SPRING FORCE?

- Represented by Fs
- Something STRETCHING or COMPRESSING
- When a SPRING or RUBBER BAND causes something to move
- Requires contact

What is BUOYANT FORCE?

- Represented by FB
- Floating in the AIR, WATER, or ANOTHER FLUID
- Requires contact

What is ELECTROSTATIC FORCE?

- Represented by FE
- STATIC ELECTRICITY
- STATIC ELECTRICITY holding something up
- Does NOT require contact

How is the force of GRAVITY affected by the CLOSENESS of two objects?

- The CLOSER the objects, the GREATER the gravitational force

- The FARTHER the objects, the SMALLER the gravitational force

How is the force of GRAVITY affected by the MASS of two objects?

- The SMALLER the mass, the SMALLER the gravitational force

- The BIGGER the mass, the GREATER the gravitational force

What is "g"? (Think of Fw \= mg)

The STRENGTH of gravity
- it is a constant for a planet.
- depends on the size of the planet
- this is why weight changes when you change planets!!!!!!!!!
- (strength of Earth's gravity is 9.8 N/kg (or 9.8 m/s2))

How do you find the PERCENT CHANGE?

% Change \= (Final value - starting value)/starting value · 100

➵ Example - increasing the height of the ramp's effect on speed

(10th hole (final) - 5th hole (starting))/5th hole · 100 \= 100%
(178 cm/s - 128 cm/s)/128 cm/s · 100 \= 39%

A 100% increase in height caused a 39% increase in speed

What is LINEAR REGRESSION and what does it mean on graph?

- Used to determine if there is a relationship between two variables
- Also used to predict a dependent variable based on a given independent variable.

➵ (Trendline aka line of best fit - a line that goes through most of the data [shows a general course of change])

R2 - Correlation Coefficient
- 0.95 and up - very strong relationship between the variables
- 0.9 and up - strong relationship between the variables
- 0.5 and up weak relationship or you messed up your measurements.
- < 0.5 - no relationship or you messed up your measurements

Even though us humans have a gravitational force, why are objects not orbiting around us?

Because we are TOO SMALL and do not have the mass of billions of kilograms (unless you do then A HUGE ROUND OF APPLAUSE YOU ARE OFFICIALLY A PLANET)

What is a FREE BODY DIAGRAM?

A diagram showing all the forces acting on an object
- Uses vectors (forces are vectors, which are numbers that show both MAGNITUDE and DIRECTION)

What TWO factors does the force of gravity depend on?

- The CLOSENESS and the MASS of two objects
- The force of gravity results from the interaction of 2 or more objects

What is NET FORCE?

The total forces acting on an object
- net force can be negative if the direction of the biggest number is going left

What is the relationship between weight and the force of gravity?

They are THE SAME THING

What is the relationship between MASS and LOCATION?

No matter where you are or where something is, the mass of the object remains the same

What is a balanced force/EQUILIBRIUM?

When all forces cancel each other out or they are EQUAL
- net force \= 0
- forces are in equilibrium

What is an UNBALANCED FORCE?

When there is a net force and not all forces are canceled out (NOT EQUAL)
- NET FORCE \> 0

What is NEWTON'S FIRST LAW?

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force
- The law of INTERIA

➵ No net force (force \= 0 N)
- Stationary objects stay still
- Moving objects keep moving
- Objects do not accelerate

➵ Net force (force \> 0 N)
- Objects change their motion
- Objects accelerate

What is INTERIA?

The tendency of an object to resist a change in motion
- How mass reacts to motion
- MORE MASS \= HARDER TO CHANGE THE MOTION (harder to speed up, slow down, and turn)

What is NEWTON'S SECOND LAW?

F \= ma
- FORCE \= MASS x ACCELERATION
- MASS \= FORCE ÷ ACCELERATION
- ACCELERATION \= FORCE ÷ MASS
➵ UNIT - Newtons (N)

What does Newton's Second Law REVEAL?

- Force INCREASES acceleration
- Mass REDUCES acceleration

What is ACTION/REACTION FORCE?

- Action is the force exerted by the first object, reaction is the force exerted by the second object
- They are OPPOSITES of each other

What is MOMENTUM?

A number that expresses how hard it will be to STOP an object
- Relationship between mass and speed (REPRESENTED BY p)
- More mass \= more momentum
- More speed \= more momentum
- p \= mv (Momentum (p) \= mass · velocity

➵ Conservation of Momentum
In a collision, the TOTAL momentum of a system before a collision ALWAYS EQUAL to the total momentum after the collision
- We can use this to predict the speed of objects after collisions

What is Newton's Third Law?

For every action there is an equal and opposite reaction
- The forces act at the same time
- Forces come in pairs.
- Forces are an interaction between two objects.
- This means that if object A pushes on object B, then object B pushes on A with the same size force but in the opposite direction

➵ Ex.
Action force: Man kicks the horse (he mad)
Reaction force: The body of the horse applies a force the to man (probably breaking his foot) (lol)

Why don't the forces cancel each other out?
- Because it is NOT acting on the same object!!!!!!!

While traveling in space, a spaceship is moving at 2.1 miles per second. How fast will the craft be moving in 1 hour?

2.1 miles per second
➵ WHY?
- There is NO net force applied which means that the spaceship is moving at a constant speed in space

If the mass of an object is increased, but the force pushing on it stays the same, what happens to the acceleration?

It decreases
➵ WHY?
- Remember: MASS REDUCES ACCELERATION

Kyela and her brother are roller skating. Kyela has a mass of 70 kg and her brother has a mass of 40 kg. When Kyela pushes off her brother, how do their accelerations compare?

The acceleration is slower
➵ WHY?
- Because she is heaver ANDDDDD mass REDUCES acceleration

What are the TWO kinds of energy?

Kinetic and potential

What is KINETIC ENERGY?

The energy an object has due to its motion
- Measured in JOULES (J)

KINETIC ENERGY \= 1/2 x MASS (m) x VELOCITY (v^2)

Variations:
MASS \= 2 x KINETIC ENERGY / VELOCITY
VELOCITY \= √2 x KINETIC ENERGY / MASS

What does KINETIC ENERGY depend on?

The MASS and SPEED of the object
- The heavier something is, the more kinetic energy it has
- The faster something is, the more kinetic energy it has

What is POTENTIAL ENERGY?

Energy that is stored
- Measured in JOULES (J)

POTENTIAL ENERGY \= MASS x GRAVITY (9.8 m/s2) x HEIGHT

➵ Variations:
- MASS \= POTENTIAL ENERGY / GRAVITY (9.8 m/s2) x HEIGHT
- HEIGHT \= POTENTIAL ENERGY / GRAVITY (9.8 m/s2) x MASS

➵ Gravitational potential energy
- Directly proportional to the height of an object and the mass of an object
- The higher the object the more potential energy.
- The larger the object the more potential energy.

What does POTENTIAL ENERGY depend on?

The MASS and HEIGHT of the object
- The higher the object, the more potential energy it has
- The heavier the object, the more potential energy it has

What is ENERGY?

Anything that can cause matter to MOVE or is able to TRANSFORM IT
- Often classified into two groups: Potential and Kinetic

➸ Total energy \= the potential energy + the kinetic energy
- Total energy - potential \= kinetic
- Total energy - kinetic \= potential
- Kinetic + potential \= total energy

- The amount of work required to get an object to the top of a ramp is EQUAL to the potential energy at the top
- As an object falls potential energy changes into an EQUAL amount of kinetic energy
- The total amount of energy in a system remains CONSTANT

What are the SIX types of energy?

- Mechanical (Both potential and kinetic)
- Chemical (Potential)
- Nuclear (Potential
- Radiant (Kinetic)
- Electrical (Kinetic)
- Thermal (Kinetic)

What is CHEMICAL ENERGY?

Energy stored in the BONDS between ATOMS
Examples:
- Food
- Fuels (like gasoline)
- Natural Gases
- Coal

What is ELECTRICAL ENERGY (Electricity)?

Energy caused by the MOVEMENT of ELECTRONS

Examples:
- Batteries
- Lightning
- Electrical appliances (like refrigerators and computers)
- Wind turbines

What is MECHANICAL ENERGY?

Energy that is possessed by an object due to its MOTION or POSITION
- Anything that COULD move has mechanical POTENTIAL energy
- Anything that MOVES has mechanical KINETIC energy

Examples in everyday life:
- Breathing in and out
- Riding a bicycle
- Listening to music
- Sharpening a pencil

What is NUCLEAR ENERGY?

Energy that is stored within the NUCLEUS of an ATOM

- Think of the SUN 🌞

What is RADIANT ENERGY?

Energy that is carried in ELECTROMAGNETIC WAVES
Examples:
- Light
- Heat
- X-rays
- Radio frequencies

What is THERMAL ENERGY?

Energy due to the MOTION OF PARTICLES in an object or system that causes a change in temperature

Examples:
- Warmth from the sun
- A hot drink
- Baking in an oven
- Heat from a heater

What is a SYSTEM?

A group of things that is important to a singular thing you are studying (everything else is excluded)

What is the LAW OF CONSERVATION OF ENERGY?

Energy is CONVERTED from one form to another
- IT CAN NOT BE CREATED OR DESTROYED!

- As kinetic energy INCREASES the potential energy DECREASES by the SAME AMOUNT
- As potential energy INCREASES the kinetic energy DECREASES the SAME AMOUNT

➸ As an object falls, the height will DECREASE and the speed will INCREASE in such a way that the amount of potential energy lost is EQUAL to the kinetic energy gained
- HEIGHT is the most important factor

What is WORK?

How much FORCE is applied over a DISTANCE
- The FORCE and DIRECTION OF MOTION must be either in the SAME DIRECTION or 180 DEGREES

WORK (J) \= FORCE (N) x DISTANCE (m)WORK (J) \= kg x m/s^2 x DISTANCE (m)

➸ Variations:
FORCE \= WORK (J) / DISTANCE (m)
DISTANCE \= WORK (J) / FORCE

➵ More info:
- Measured in Joules (J)
- The amount of work done is equal to the amount of energy the object has after the work is FINISHED

What does POTENTIAL ENERGY at the HIGHEST POINT and KINETIC ENERGY at the LOWEST POINT tell us?

Both of these scenarios tell us the TOTAL AMOUNT OF ENERGY
- At the highest point, the kinetic energy would be 0 J
- At the lowest point, the potential energy would be 0 J

A strong person lifts a 1700 N weight 2.0 m in the air. How much work did they do?

3400 J

➵ Calculations: (NEVER FORGET SIGNIFICANT FIGURES!)
WORK \= FORCE (N) x DISTANCE (m)
WORK \= 1700 N x 2.0 m \= 3400 J

What is POWER?

The rate at which work is done or energy is transferred

➵ P \= W/t
- POWER \= WORK/TIME
- TIME \= WORK/POWER
- WORK \= POWER · TIME

If you go twice as fast, your kinetic energy becomes:

FOUR times greater

Where is the HIGHEST potential energy found?

At the HIGHEST point

Where is the HIGHEST kinetic energy found?

At the LOWEST point

As a ball is thrown in the air, what is happening to its kinetic and potential energy over time?

- Potential energy INCREASES
- Kinetic energy DECREASES

What is ELECTROMAGNETIC FORCE?

(AKA electric force) The interaction between charged particles

- Opposite charges ATTRACT
➵ + ❤️ -

- Same charges REPEL
➵ + 💔 +
➵ - 💔 -

What is a CHARGE?

The value for electricity flowing in a circuit
- ALL MATTER HAS CHARGE

➵ INTERACTIONS BETWEEN CHARGES
- Neutral charge \= the amount of positive and negative charges are EQUAL
- Positive charge \= the amount of negative charges are FEW
- Negative charge \= the amount of negative charges are MORE THAN positive charges

ONLY NEGATIVE CHARGES MOVE

What is STATIC ELECTRICITY?

An imbalance of charges that occurs when electrons move in an insulator
- AKA a buildup of charges on an object

REMEMBER THE VAN DER GRAAF GENERATOR?
- That is the same thing! It is a shock that occurs when you have a buildup of charge and touch a conductor. The shock you feel is the negative charges moving to make you neutral again. CRAYYZZ 😺