Homework Video

Review of… (don’t write this down!) • Unit Conversions

• SI (System Internationale) – base units of measurement – distance – meter (m)

– time – second (s)

– speed – meter per second (m/s)

– mass – gram (g)

– force – newton (N)

– energy – joule (J)

– volume – liter (L)

• SI system uses prefixes to convert units…

Review of… BASE UNIT

Move decimal to right (multiply)

Move decimal to left (divide)

Review of… • Examples: Convert the following…

A) 150cm = 1.5 m

B) 0.00054g = 540 µg

C) 6.3 km = 6300 m

D) 5500mL = 5.5 L

Review of… • Scientific Notation

• Used to easily represent very large or very small numbers.

• Written with ONE digit before the decimal, then multiplied by a power of 10.

• Large numbers have positive exponents.

• Small numbers have negative exponents.

• Eg. 4.36 x 107 m = 43 600 000 m

• Eg. 3.11 x 10-4 kg = 0.000 311 kg

Review of… • Examples: Express the following in scientific

notation…

A) 3 160 000 000 N = 3.16 x 109 N

B) 0.000 000 000 007 721 g = 7.721 x 10-12 g

Review of… • Algebra

• When doing calculations, order matters. – BEDMAS (brackets, exponents, divide, multiply,

add, subtract)

• When doing algebra, you do BEDMAS backwards (SAMDEB??)

• Remember, what ever you do to one side, you MUST do to the other!!!

Review of… • Examples: Solve the following equations for

“y”… A) 2x + y = 6 y = -2x + 6

B) x – y = 3 y = x – 3

C) y/2 = 6x y = 12x

D) 3x – 2y = 5 y = (3/2)x - 5/2

Homework: Review Worksheet

Significant Digits (Write this down!) • When given a number, only certain digits are

considered significant (accurate); all other numbers are uncertain (rounded). – Eg. This dinosaur is 65 000 003 years old!

• Rules for Significant digits: – Digits 1 to 9 are always significant (231 has 3SD)

– Zeros between digits 1 to 9, and zeros at the end of the number are significant (406.20 has 5 SD)

– Leading zeros are NOT significant (0.0023 has 2 SD)

Significant Digits • Examples: Determine the number of

significant digits in the following…

A) 307.0 cm has 4 SD

B) 61 m/s has 2 SD

C) 0.03 kg has 1 SD

D)0.5060 km has 4 SD

E) 3.00 x 108 m/s has 3 SD

Note: Exponents of scientific notation are NOT significant digits

Significant Digits • Significant Digits and Math

• When multiplying or dividing, the answer has the same number of SD as the measurement with the FEWEST SD.

• EX. Determine the area of a triangle which has a base of 3.2cm and a height of 10.1cm.

• EX. 312 x 4610

Significant Digits • When adding or subtracting, the answer has

the same number of decimal places as the measurement with the fewest decimal places.

• EX. Three people share driving on a road trip. If one person drove 104 km, the second person drove 86.5 km, and the third person drove 98 km, what was the distance of the road trip?

Homework: Significant Digits Worksheet

Scalars and Vectors • All quantities are classified as either scalars

or vectors.

• Scalar – quantity with MAGNITUDE only. (“How much?”)

• Eg. time, mass, distance, speed

• Vector – quantity with MAGNITUDE and DIRECTION (“How much & which way?”)

• Eg. force, displacement, velocity

Distance vs. Displacement • Distance (d) – total distance travelled from

start to finish.

• Direction is irrelevant: scalar

• Like odometer in a car. – Eg. Distance to Red Deer from Edmonton, while going

through Calgary, 600 km.

• Displacement (d) – straight line distance between start and finish.

• Direction is needed: vector – Eg. Displacement to Red Deer from Edmonton, 200

km [S]

Distance vs. Displacement

Distance vs. Displacement • EX. Determine the distance and

displacement of the following…

3 km

6km

START

FINISH

Right/East & Up/North are POSITIVE

Left/West & Down/South are NEGATIVE

Speed vs. Velocity • Speed (v) – distance traveled over a period

of time. (Usually measured in m/s or km/h)

• Speed is a scalar (eg. v = 20 m/s)

• Velocity (v) – displacement over a period of time. (Usually measured in m/s or km/h)

• Velocity is a vector (eg. v = 20 m/s [N])

Formula: v = d OR v = d t t

Speed vs. Velocity • EX. 1) A boat travels 200m [N] in 20s.

Calculate the average speed and velocity.

• 2) The same boat turns and travels 400m [S] in 30s. Determine the average speed and velocity for the entire trip.

Speed vs. Velocity • 3) A car with a velocity of 33m/s [E] travels

for 3.2 hours. What is its displacement?

• 4) How long does it take a sprinter to cover 100m with an average speed of 14m/s?

Homework: Scalar & Vector Wkst

Graphing • All graphs require the following…

• 1. Title

• 2. Manipulated variable on x-axis (usually time), responding variable on y-axis.

• 3. Labels for axes, including units

• 4. Proper scales (start at zero, increase at a constant rate)

• 5. Line of best fit (note: does NOT always need to be straight)

• 6. Legend if necessary

Graphing

Types of lines of best fit

What are some errors in these graphs?

Graphing • Example: Graph the following

Time (s) Distance (m)

0.0 0.0

1.0 0.9

2.0 2.1

3.0 3.3

4.0 3.8

5.0 5.0

6.0 6.1

7.0 7.2

Graphing • Calculating slope

• 1. Determine the coordinates of two points on the line of best fit.

• 2. Use the slope formula to calculate the slope (do not forget units and SD)

slope = rise = y2 – y1 = m run x2 – x1

Calculate the slope of the previous graph

Bubble Gum Lab

Motion • Two types:

• Uniform motion – Object travels at a constant rate of motion (constant speed)

• Non-uniform motion – Objects motion is not at a constant rate (speed is changing, acceleration/deceleration)

• Graphs can be used to represent motion of an object.

• Two types: Distance-time graphs or Speed-time graphs

Distance-time Graphs • Slope of D-T graph is…

• m = rise/run = d/t

• And we know that d/t = v, therefore…

• The slope of a D-T graph is SPEED!

• Explain what each graph represents…

Distance-time Graphs • Explain what you know about the motion of

each object, given the following D-T graphs

Homework: Pg 130 #4, Pg 135 #2, 5, 8, 9, 12, 16, 18

A

B

C

d

t

D

E

F

d

t

Ticker Tape Lab

Speed-time Graphs • What information about the motion of an

object can we obtain from a V-T graph?

v

t

v

t

Uniform Motion

(Constant Speed)

Non-Uniform Motion

(Acceleration)

Note: The slope of a V-T graph is acceleration

Speed-time Graphs • We can determine the total distance

traveled by an object by calculating the area under a V-T curve.

Speed-time Graphs • Example: Determine the total distance an

object has traveled using the V-T graph

V

(m/s)

0 t (s)

13

6.0

Speed-time Graphs • Example: Determine the total distance an

object has traveled using the V-T graph

V

(m/s)

0 t (s)

12

8.0

Summary of Motion Graphs

d d d

t t t

no motion uniform motion non-uniform motion

v

t

v

t

uniform motion non-uniform motion

Homework: Pg 133 #5, Pg 135 #4, 6, 10, 11, 13, 14

Physics Quiz

Acceleration • Acceleration (a) – a change in speed or

velocity over a period of time. – We will treat acceleration as a scalar.

Formula: a = Δv = vf – vi

t t

• There are two types of acceleration: • Positive – object is speeding up • Negative – object is slowing down (deceleration) • Units for acceleration: m/s2

Acceleration • Examples:

• 1) A dirt bike rider can change speed by 17m/s in 10.0s. What is the magnitude of the rider’s acceleration?

• 2) A dog runs down a hill with an initial speed of 12.0m/s. It takes the dog 3.60s to reach the bottom of the hill, where his final speed is 18.0m/s. Determine the dog’s acceleration.

Acceleration • 3) A car has an acceleration of -0.40m/s2.

If the car starts with a speed of 31.0m/s, what is the magnitude of its final speed after 9.3s?

• 4) A rocket with acceleration of 37.63m/s2 started its flight at rest. How long does it take the rocket to reach a final speed of 2965m/s?

Homework: Uniform Acceleration Worksheet

Motion Review • Pg 162 #1-5, 9-13, 15-20, & 25-28

Motion Test

Force • Force – a push or pull on an object

• Balanced forces – causes uniform motion. Object will remain at rest, or remain at a constant velocity.

• Unbalanced forces – causes acceleration (positive or negative). Object will speed up or slow down. – Imagine a car accelerating from rest, putting on

cruise control, then hitting a wall.

• Measured in Newtons (N) 1N = 1kgm/s2

Work • Work – Applying a force over a certain

distance.

• 3 conditions for work to be done: – 1. There must be a force applied to the object

– 2. The object must move a distance

– 3. The force and distance must be in the SAME direction. • (Holding a book up, and walking across the room is

NOT work!)

Work • Formula: W = Fd

• Work is measured in Joules (J) 1J = 1Nm

• EX: Determine the work done by a crane that lifts a beam 15m into the air by applying a force of 6.5kN.

Energy • Energy – the ability to do work.

• You can transfer energy to an object by doing work.

• The amount of work done on an object is EQUAL to the energy change in the object.

• Formula: W = ΔE

• Energy is measured in Joules (J) (same as work)

Energy • EX: If 1.4 x 105N of force is applied to raise

a box 0.962m, how much energy does the box gain?

Homework: Pg 160 #18-20 & Pg 161 #1-10, omit 3

Types of Energy • Remember: Energy – the ability to do work

– Work – the transfer of energy

• Types of energy: – Chemical – energy stored in chemical bonds

– Electrical – energy in moving charges

– Nuclear – energy stored in nucleus of atom

– Solar – energy stored in H-H fusion reaction

– Thermal – vibration energy of atoms (heat)

– Gravity – energy stored in position (height)

– Note: there are many other forms of energy: sound, geo-thermal, magnetic, wind, etc.

Types of Energy • All forms of energy can be grouped into 2

categories:

• 1) Kinetic Energy – Energy due to motion. – Eg. a car moving, water flowing, wind blowing

– Anything with speed has kinetic energy

• Formula: Ek = ½mv2

• 2) Potential Energy – potential to do work (stored energy) – Eg. gravity, chemical, nuclear, magnetic

Types of Energy • We will look at gravitational potential energy.

• Formula: Ep = mgh

• g = gravitational field strength = 9.81m/s2

• Examples:

• 1) Determine the kinetic energy of a 6.5kg ball moving at 4.82m/s.

• 2) A 148.5kg beam is lifted 120.0m in the air. How much potential energy did it gain?

Homework: Pg 172 #13-14, Pg 178 #4-7, Pg 182 #5-6

Mechanical Energy • Mechanical Energy – the sum of the kinetic

and potential energy of a system.

• Formula: Em = Ek + Ep

• EX: Determine the mechanical energy of an airplane flying 1200m above the ground at a speed of 256m/s.

• Law of Conservation of Energy – Energy cannot be created or destroyed, only changed from one form to another. – The mechanical energy of a system remains constant.

Homework: Pg 188 #1-3, 7

Energy Conversions in Nature • We get our energy from the Sun.

• Plants use photosynthesis to convert solar energy into chemical energy (glucose)

• Animals eat plants to obtain glucose, then convert it into ATP energy for muscles.

• Energy from fossil fuels (oil, coal, and gas) also get their energy from the Sun. – Remains from dead plants and animals are

converted to fossil fuels over tens of millions of years, using extreme heat and pressure.

Electrical Energy Conversions • Hydroelectric Dams – Water held in a

reservoir behind a dam. A penstock allows water to flow through the dam, which turns a turbine, which turns a generator, producing electricity.

• Energy conversions: Gravitational potential energy of energy kinetic energy of water kinetic energy of turbine/generator electrical energy

Electrical Energy Conversions • Thermoelectric Power Plant: Coal is burned

to heat water to produce steam. Steam is pressurized, and used to turn a turbine. The turbine turns a generator, which produces electrical energy.

• Energy Conversions: Chemical energy thermal energy kinetic energy of steam kinetic energy of turbine/generator electrical energy.

Electrical Energy Conversions • Thermonuclear Power Plant: Uranium

undergoes radioactive fission, which creates heat. Heat used to heat water to steam, which turns a turbine, which turns a generator, which produces electricity.

• Energy Conversions: Nuclear energy thermal energy kinetic energy of steam kinetic energy of turbine/generator electrical energy.

Electrical Energy Conversions • Other forms of electrical energy production:

• Wind energy: uses windmill to turn generator

• Solar energy: uses sunlight directly

• Fuel cells (batteries): uses chemical energy to create electricity

Homework: Pg 195 # 1, 2, 4, 8, 9, 10

Laws of Thermodynamics • System: a set of interconnected parts that

are responsible for energy conversions. – Eg. An engine in a car is a system, and the other

parts of the car (windshield wipers, seat, mirrors, etc) are considered the surroundings.

Laws of Thermodynamics • There are 3 types of systems:

• 1) Open – exchanges both matter and energy with surroundings.

• 2) Closed – exchanges energy with surroundings, but NOT matter.

• 3) Isolated – Unable to exchange energy or matter with surroundings.

Heat – Transfer of ENERGY from one location to another

Work – Transfer of MATTER from one location to another

Laws of Thermodynamics • 1st Law of Thermodynamics: The total energy

in a system and its surroundings remains constant.

• In other words: Energy cannot be created or destroyed, only converted from one form to another. – It is important to remember that heat is a form

of energy, so a system that seems to be losing energy is merely transferring the energy into heat.

Laws of Thermodynamics • Perpetual Motion Machines – are machines

that convert all input energy into mechanical energy. In theory, they should run forever.

• However, there is always a small amount of friction, sound, heat, etc, which means there is a small loss of energy.

• The 1st Law of Thermodynamics states that perpetual motion machines CANNOT exist!!

Perpetual Motion Machine

Laws of Thermodynamics • 2nd Law of Thermodynamics: Heat always

flows from a hot object to a cold object.

• Heat will NEVER flow from cold to hot!

Homework: Pg 205 #2-4, 6, 7, 9, 11

Useful Energy • The purpose of a machine is to convert

energy that is added to a system into energy needed to do work.

• Input energy – Energy put into machine.

• Output energy – Energy obtained from machine. Two types:

• Useful Output energy – Energy output that is desired.

• Waste energy – All other output energy. Eg. heat, sound, light, friction, etc.

Useful Energy • Efficiency – Measurement of how effectively

a machine converts input energy into useful output energy.

Efficiency = useful output energy x 100 input energy

•Note: efficiency is a percentage, and CANNOT be larger than 100%

Useful Energy • Examples:

• 1) In lifting a car, the total input energy is 5.61 x 104 J, while the useful output energy is 1.96 x 104 J. Calculate the efficiency of the hoist.

• 2) It takes 643 J of energy to move a fan. If there is 344 J of waste energy, determine the efficiency of the fan.

Homework: Pg 220 # 1, 3, 5-9

PHYSICS REVIEW • Physics final exam review package AND

• Pg 232 #2-8, 10-11, 14, 17, 30-34, 36, 39-41, 53-55, 75

PHYSICS UNIT EXAM