Review of (don t write this down!)

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Claude Lee
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3 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

4 Review of BASE UNIT Move decimal to right (multiply) Move decimal to left (divide)

5 Review of Examples: Convert the following A) 150cm = 1.5 m B) g = 540 µg C) 6.3 km = 6300 m D) 5500mL = 5.5 L

6 Scientific Notation Review of 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 x 10 7 m = m Eg x 10-4 kg = kg

7 Review of Examples: Express the following in scientific notation A) N = 3.16 x 10 9 N B) g = x g

8 Algebra Review of 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!!!

9 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

10 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 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 ( has 5 SD) Leading zeros are NOT significant ( has 2 SD)

11 Significant Digits Examples: Determine the number of significant digits in the following A) cm has 4 SD B) 61 m/s has 2 SD C) 0.03 kg has 1 SD D) km has 4 SD E) 3.00 x 10 8 m/s has 3 SD Note: Exponents of scientific notation are NOT significant digits

12 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

13 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

14 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

15 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]

16 Distance vs. Displacement

17 Distance vs. Displacement EX. Determine the distance and displacement of the following START 3 km FINISH 6km Right/East & Up/North are POSITIVE Left/West & Down/South are NEGATIVE

18 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 t v = d t

19 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.

20 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

21 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

22 Graphing Types of lines of best fit What are some errors in these graphs?

23 Graphing Example: Graph the following Time (s) Distance (m)

24 Calculating slope Graphing 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 = y 2 y 1 = m run x 2 x 1 Calculate the slope of the previous graph

25 Bubble Gum Lab

26 Two types: Motion 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 Speedtime graphs

27 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

28 Distance-time Graphs Explain what you know about the motion of each object, given the following D-T graphs d A d F B C t D E t Homework: Pg 130 #4, Pg 135 #2, 5, 8, 9, 12, 16, 18

29 Ticker Tape Lab

30 Speed-time Graphs What information about the motion of an object can we obtain from a V-T graph? Non-Uniform Motion (Acceleration) v Uniform Motion (Constant Speed) v t t Note: The slope of a V-T graph is acceleration

31 Speed-time Graphs We can determine the total distance traveled by an object by calculating the area under a V-T curve.

32 Speed-time Graphs Example: Determine the total distance an object has traveled using the V-T graph V 13 (m/s) 0 t (s) 6.0

33 Speed-time Graphs Example: Determine the total distance an object has traveled using the V-T graph V 12 (m/s) 0 t (s) 8.0

34 Summary of Motion Graphs d d d t t t no motion uniform motion non-uniform motion v v t t uniform motion non-uniform motion Homework: Pg 133 #5, Pg 135 #4, 6, 10, 11, 13, 14

35 Physics Quiz

36 Acceleration Acceleration (a) a change in speed or velocity over a period of time. We will treat acceleration as a scalar. Formula: a = Δv = v f v i t t There are two types of acceleration: Positive object is speeding up Negative object is slowing down (deceleration) Units for acceleration: m/s 2

37 Examples: Acceleration 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.

38 Acceleration 3) A car has an acceleration of -0.40m/s 2. 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/s 2 started its flight at rest. How long does it take the rocket to reach a final speed of 2965m/s? Homework: Uniform Acceleration Worksheet

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

40 Motion Test

41 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/s 2

42 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!)

43 Formula: W = Fd Work 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.

44 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)

45 Energy EX: If 1.4 x 10 5 N 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

46 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.

47 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: E k = ½mv 2 2) Potential Energy potential to do work (stored energy) Eg. gravity, chemical, nuclear, magnetic

48 Types of Energy We will look at gravitational potential energy. Formula: E p = mgh g = gravitational field strength = 9.81m/s 2 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

49 Mechanical Energy Mechanical Energy the sum of the kinetic and potential energy of a system. Formula: E m = E k + E p 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

50 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.

51 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.

52 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.

53 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.

54 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

55 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.

56 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

57 Laws of Thermodynamics 1 st 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.

58 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 1 st Law of Thermodynamics states that perpetual motion machines CANNOT exist!! Perpetual Motion Machine

59 Laws of Thermodynamics 2 nd 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

60 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.

61 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%

62 Examples: Useful Energy 1) In lifting a car, the total input energy is 5.61 x 10 4 J, while the useful output energy is 1.96 x 10 4 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

63 PHYSICS REVIEW Physics final exam review package AND Pg 232 #2-8, 10-11, 14, 17, 30-34, 36, 39-41, 53-55, 75

64 PHYSICS UNIT EXAM

CHAPTER 13.3 AND 13.4 ENERGY

CHAPTER 13.3 AND 13.4 ENERGY Section 13.3 Energy Objective 1: What is the relationship between energy and work? Objective 2: Identify the energy of position. Objective 3: The factors that kinetic energy