d = +20 m symbol units direction magnitude PHYSICS Quantities that can be measured by using an instrument and have specific units of measurement.

Transcription

1 GROUP ACTIVITY PHYSICS PERIODS 2 & 6 UNIT 1 Introduction to Physics Work with your group. Take a chart from the front table and tape it on your Physics notebook. Take 5 instruments and make measurements (your group decides what to measure). Complete the chart. Be ready to participate in class. MR. LARGO MR. Hill INSTRUMENT A Device used to measure physical quantities. Examples: Meter stick, thermometer, spring scale, graduated cylinder, stop watch, Multimeter. PHYSICAL QUANTITY Quantities that can be measured by using an instrument and have specific units of measurement. Mass EXAMPLES OF PHYSICAL QUANTITY Force (weight) Clock reading (time) Distance (length) Volume 1. Symbol 2. Direction 3. Magnitude 4. Units ELEMENTS OF PHYSICAL QUANTITIES d = +20 m symbol units direction magnitude 1

2 SYMBOL DIRECTION Short representation of a The place towards which an object is directed MAGNITUDE UNITS The number of a physical quantity Standard adopted to measure a Metric System (world) English system (USA) The number of a The place towards which an object is directed. Quantities that can be measured by using an instrument and have specific units of measurement DIRECTION INSTRUMENT SYMBOL Standard adopted to measure a A Device used to measure physical quantities. Short representation of a physical quantity PHYSICAL QUANTITY MAGNITUDE UNITS 2

3 PHYSICS CLASS We work with physical quantities such as mass, distance, velocity, etc., that can be measured with an instrument such as spring scale, meter stick, speedometer. We do not deal with feelings or emotions such as love, happiness, sadness, etc. PLEASE 4 VOLUNTEERS TO THE FRONT OF THE ROOM! TAKE OUT YOUR PERSONAL TELESCOPE MOTION An object is in motion with respect to another object (reference object) if, as time progresses, its position changes relative to a reference object. REFERENCE FRAME THE ROBOT ACTIVITY Who wants to be a robot for the day? A tool used by physicists to make a specific description of an object s motion. 3

4 ELEMENTS OF A REFERENCE FRAME 1. An object of reference 2. A coordinate system with a scale for measuring distance 3. Clock readings SETTING A REFERENCE FRAME EXAMPLE: Jordan bats a baseball 20 m away from home plate and the ball lands 15 s later. What to do? Sketch the situation Identify and circle your system Set the reference frame SETTING A REFERENCE FRAME SETTING A REFERENCE FRAME EXAMPLE: Jordan bats a baseball 20 m away from home plate and the ball lands 15 s later. SKETCH: Drawing of the given situation SYSTEM: The object we choose to analyze (circle it). d x =0 m t 0 = 0 s 1. Identify the object of reference d x [m] t f = 15 s 2. A coordinate system with a scale for measuring distance 3. Clock readings WHITEBOARD WHITEBOARD MAKE UP A WORD STORY Luisa rides her bike 100 m in 20 s towards the left. Set the reference frame. d x0 =0 mi t 0 =0 hour d x [m] t F = 20 s d x =0m t 0 =0s d x =2860 mi t F =6 hours 4

5 LINEAR MOTION It is a model of motion that assumes that an object, considered as a pointlike object, moves along a straight line. Particle Dimensionless object (point-like object) The runner is the object of interest (system) moving toward a person on a bench. The runner moves in a straight line (linear motion) The runner is now represented with a particle to simplify the physics. I am Usain Bolt! PHYSICS Science that studies MODELS of real life situations. These MODELS are not perfect and are limited. EXAMPLES OF MODELS Particle model Mathematical models Linear Motion Projectile Motion Circular Motion TYPES OF PHYSICAL QUANTITIES PHYSICAL QUANTITY Vectors: Physical quantities that require of a magnitude (number) and direction. Scalar: Physical quantities that require of a magnitude (number) only. CLOCK READING (time): The reading from a stop watch when an object moves between two points. Name Symbol Units Units symbol Type of PQ Clock Reading t seconds s Scalar (doesn t need direction) 5

6 POSITION Location of an object with respect to a particular coordinate system. Name Position Symbol dx Type of PQ Vector (needs direction) d X DISPLACEMENT Vector that starts from an object initial position and ends at its final position. Also known as change in position Difference between two positions. Final position minus initial position. Math model: dx = dx f dx i Name Displacement Symbol dx d X DELTA Greek letter DELTA ( ) Physics meaning: change between two physical quantities We need to have two of the same kind: Initial & Final DISTANCE The magnitude (length) of the displacement vector (direction does not matter). Name distance Symbol d d Type of PQ scalar (doesn t need direction) DISTANCE VS. DISPLACEMENT Distance and Displacement have the same magnitude. Distance is a scalar (Only magnitude is needed) Displacement is a Vector (Magnitude and direction are needed. Distance is the magnitude of the Displacement. PATH LENGTH Length of a string laid along the path the object took. Name Path length Symbol L Type of PQ scalar L 6

7 PIKACHU BULBASAUR CHARMANDER SQUIRTLE JIGGLYPUFF MEW 7