Unit 1 Basics and 1 D Motion Objectives

Unit 1: Basics and 1 D Motion Objectives: Understand selected metric units and prefixes and know how to find them on the NYS Reference Tables Be able to set up and calculate simple conversions Identify difference between scalar/vector, distance/displacement, speed/velocity Define acceleration and perform calculations using its equation Perform calculations using given equations for 1 D motion Perform calculations for free falling problems

I. Measuring & Units Precise: repeated measurements/ calculations that show similar results Accurate: degree of correctness High accuracy, low precision High precision, low accuracy

I. Measuring & Units Base Units – standard unit of measurement The three base units we will use the most in this course are: SI Base Units Base Quantity Base Unit Symbol • Length • meter • m • Mass • kilogram • kg Time • second • • s

I. Measuring & Units Remember: We will only be using the metric system in this course, so here are some useful ways of relating the English System (US’s measurement) to the rest of the world 1 kg = 2. 20 lb = approximate mass of a textbook (175 lb person = 79 kg) 1 m = 3. 28 ft = approximate height of a doorknob (a basketball hoop (10 ft) = 3. 05 m)

I. Measuring & Units Derived Units: Combination of base units Example: m/s, miles/hr Velocity/speed are measured in _______ m/s/s Acceleration is measured in _____

II. Metric System • Metric system has two parts: 1. Base Unit 2. Prefixes • Prefixes multiply or divide the base units by 10 multiples of ________ • Powers of Ten Video (9 min)

Metric Prefixes Prefix Symbol Meaning As a number Example kilo- k thousand 1000 1 kg = 1, 000 g centi- c hundredth 0. 01 1 c. L = 0. 01 L milli- m thousandth 0. 001 1 ms = 0. 001 s Are Imperial units outdated? (3 min) Time to switch to Metric (3 min)

II. Metric System Conversion Practice 1. A common race is the 5 K, which is 5 kilometers. How many meters is this? Given Units: Units Wanted: Conversion scale: Set up and answer:

II. Metric System Conversion Practice 2. The recommended daily requirement of vitamin C is 0. 5 g. How many milligrams is this? Given Units: Units Wanted: Conversion scale: Set up and answer:

II. Metric System Practice Problems 1. 0. 553 km 2. 3, 000 m 3. 0. 50 m 4. 100 m. A 5. 0. 003 kg

1 Dimension Kinematics Trailer Here are some of the things we will be studying during this part of the unit

III. Scalar vs. Vector Quantity: • Scalar Quantity: A measurement/quantity MAGNITUDE (SIZE) that has just ________ Examples: time, temperature, distance, speed, mass, energy • Vector Quantity: A measurement/quantity DIRECTION MAGNITUDE that has _______ and _____ www. youtube. com/watch? v=A 05 n 32 Bl 0 a. Y Examples: velocity, acceleration, force, momentum

IV. Distance vs Displacement: SCALAR • Distance: ______ quantity; Total LENGTH ______ of path traveled VECTOR • Displacement: _____ quantity, Change POSITION in _____ (Final – initial position)

IV. Distance vs Displacement: Example: Joe has a date with Jill. Her house is 5 km east of his, but he has to do some things before he picks her up. He first heads 7 km N of his house to get flowers. He then travels 5 km east to pick up the movie tickets. Then he heads to her house. What was the distance he traveled? What was his displacement?

IV. Distance vs Displacement: Example: Usain “Lightning” Bolt runs around the track (400 m) in a time of 44. 0 s. What was the distance he traveled? What was his displacement?

V. Speed vs. Velocity: SCALAR • Speed: ______ quantity; How fast an object is moving (If you are traveling 80 mph, how does it take you to travel 80 miles…) v = speed (m/s) • Equation: d = distance (m) t = time (s) • Instantaneous Speed: Speed at an given instant (what your speedometer gives you)

V. Speed vs. Velocity: • Instantaneous Speed: Speed at an given instant (what your speedometer gives you) • Example: What is the average speed of a cheetah that sprints 100 m in 4 s?

V. Speed vs. Velocity: • Example: A car moves with a speed of 30 m/s. Answer the following: How far would it travel if it moved at this speed for 30 s? How far would it travel if it moved at this speed of 60 s?

V. Speed vs. Velocity: • Example: If a car moves at 20 m/s, how long does it take for it to travel 500 m?

V. Speed vs. Velocity: VECTOR • Velocity: ______ quantity; Speed with DIRECTION ___________ • Example: A car drives around a circular track at a constant speed of 65 mph. Is its velocity changing? Explain YES! Same speed (65 mph), but it is changing its direction.

V. Speed vs. Velocity: • Example: The speedometer of a car moving to the east reads 100 km/hr. It passes another car that moves to the west at 100 km/hr. Do both cars have the same speed? Explain YES, Same speed (100 mph). Do both cars have the same velocity? Explain NO, they are moving at OPPOSITE DIRECTIONS

VI. Speed vs. Velocity: • Practice Problems: 1. Speed is the rate at which what happens? Distance changes 2. What is the difference between speed and velocity? Speed is scalar (just magnitude), velocity is a vector (magnitude and direction) 3. Calculate the average speed of a bird flying 140 meters in 5 seconds. 28 m/s 4. A boy is running 5 m/s. How far does the boy run after 15 s? 75 m 5. A man walks 3 m east then 2 m west. What is the distance he traveled? What is the man’s displacement? (Hint: Sketch out the Distance = 5 m, Displacement = 1 m East man’s path)

VI. Acceleration: VECTOR • _________ quantity VELOCITY • How quickly _________ changes • Acceleration Equations (see reference table): a = acceleration (m/s/s or m/s 2) v = velocity (m/s) t = time (s) Units: m/s/s or m/s 2

VI. Acceleration: HOW TO COMPLETE ANY PHYSICS PROBLEM: 1. List givens 2. List what you want to find 3. Find correct equation and manipulate it to solve for desired variable 4. Plug in numbers with units Examples: A car starts from rest and reaches a speed of 55 m/s in 10 s. What is the car’s acceleration? Givens: Equation: Want:

VI. Acceleration: A car is traveling 55 m/s and comes to a stop in 10 s. What is the car’s acceleration? Givens: Equation: Want: Jeff Gordon is going 20 m/s and pushes down on the gas pedal and accelerates at 5 m/s 2 for 7 s. What is his final speed? Givens: Equation: Want:

VI. Acceleration: A car is accelerated at 4. 0 m/s 2 from rest. When will the car reach a speed of 28 m/s? Givens: Equation: Want:

VII. Free Fall & Acceleration due to Gravity: • Definition – acceleration due to gravity is the acceleration of an object in free fall that results from the influence on Earth’s force of gravity VECTOR • Acceleration is a _______ quantity MAGNITUDE DIRECTION (________ AND ________) 10 m/s/s • Acceleration due to gravity on Earth = ______ MASS • All objects (regardless of _____ and SIZE SAME ______) fall at the ______ acceleration (IGNORING AIR RESISTANCE) (Falcon feather on the moon)

VII. Free Fall & Acceleration due to Gravity: t = 0 s, v = 0 m/s t = 1 s, v = 10 m/s t = 2 s, v = 20 m/s t = 3 s, v = 30 m/s t = 4 s, v = 40 m/s t = 5 s, v = 50 m/s 10 m/s/s

VII. Free Fall & Acceleration due to Gravity: Penny of the Empire State Building - Mythbusters

• VII. Free Fall & Acceleration due to Gravity: Example: A 4 kg ball is dropped from rest and reaches a speed of 20 m/s. Find the time it took to reach this speed. Givens: Want: Set up and Answer Would the time change if it was a 2 kg ball? (World’s Biggest Vacuum Chamber Video 4 min) NO! MASS DOES NOT AFFECT THE RATE OF FALLING

VII. Free Fall & Acceleration due to Gravity: 1. A 70 kg skydiver falls out of a plane. Determine his final speed if he falls for 2. 5 s. 25 m/s 2. How do you think the acceleration due to gravity on the moon compares to that of Earth? Explains in terms of size (mass) comparison between Earth and Moon. The moon is much less because of its smaller mass compared to Earth 3. While on a mysterious planet an astronaut drops a feather from a height of 1 m. If the feather lands in 0. 75 s with a speed of 1. 79 m/s, determine the acceleration due to gravity on the planet. 2. 39 m/s/s 4. Based on your answer to question 3, how do you think the size (mass) of the mysterious planet compares to Earth? Smaller because of its smaller acceleration due to gravity

VII. Free Fall & Acceleration due to Gravity: Felix Baumgartner World Record Jump (4 min) Laso Schaller World Record Platform jump (2 min) (article)