Section 1: What is Motion? Matter and Motion (pg. 282) ●All matter in the universe is constantly in motion Changing Position ●Something is in motion if it is changing position ○ School building attached to Earth is moving through space ○Airplane flying, leaf swirling in wind, water trickling from a hose, etc.

Section 1: What is Motion? Changing Position (pg ) ●Relative Motion ○ Determining whether something changes position requires a point of reference ○An object changes position if it moves relative to a reference point ●Distance and Displacement ○Distance is measurement of length between two points ○Displacement is the direction and difference between starting and ending points; overall change of position Distance v Displacement

Section 1: What is Motion? Speed (pg. 284) ●The distance an object travels in a unit of time. ○Ex: an object with a speed of 5m/s can travel 5 meters in 1 second. ○Speed can be calculated from this equation: speed (in meters/second) = distance (in meters) s = d/t time (in seconds) ●SI unit for speed is m/s but speed can be calculated using other units such as kilometers for distance and hours for time.

Section 1: What is Motion? Speed (pg. 284) EXAMPLE: Calculate the speed of a swimmer who swims 100 m in 56 s. d = 100 m t = 56 s s = ? Substitute known values for distance and time into the speed equation and calculate the speed: s = 100/56 ; s = 1.8 m/s

Section 1: What is Motion? Average Speed (pg. 285) ●Average speed is found by dividing the total distance traveled by the total time taken ●Instantaneous Speed The speed of an object at one instant of time For an object travelling at a constant speed, its average speed is the same as its instantaneous speed.

Section 1: What is Motion? Graphing Motion (pg. 286) ●Distance-Time Graphs and Speed Time is plotted on the horizontal axis (the independent variable) Distance is plotted on the vertical axis (the dependent variable) A line on a distance-time graph becomes steeper as an object’s speed increases

Section 1: What is Motion? Velocity (pg. 287) The velocity of an object is the speed of the object and the direction of its motion. Ex: if a car is moving west at 80 km/h, the car’s velocity is 80 km/h west. ●The velocity of an object can be represented by an arrow Velocity can change if: speed changes direction of motion changes or they both change

Section 2: Acceleration (pg. 288) Acceleration and Motion Acceleration- change in velocity divided by the time it takes for the change to occur Acceleration has direction Acceleration occurs whenever an object speeds up, slows down, or changes direction

Section 2: Acceleration (pg. 288) Acceleration and Motion ●If an object speeds up, the acceleration is in the direction that the object is moving. ●If an object slows down, the acceleration is opposite to the direction that the object is moving.

Section 2: Acceleration (pg ) Speeding Up/Slowing Down ●Acceleration occurs whenever velocity of an object changes. When speed increases, the velocity changes so acceleration is occurring. ●If an object slows down, the velocity changes because the speed decreases. This means acceleration occurs when an object slows down, as well as when it speeds up.

Section 2: Acceleration (pg ) Changing Direction ●The velocity of an object also changes if the direction of motion changes. ●Ex: Riding a bicycle- when bike turns, the direction of the bike’s motion changes and the bicycle accelerates.

Section 2: Acceleration (pg. 290) Calculating Acceleration ●If an object is moving in only one direction, its acceleration can be calculated using this equation. final speed (in m/s) - initial speed (in m/s) time (s) a = (s f - s i ) t In this equation, time is the length of time over which the motion changes. In SI units, acceleration has units of meter per second squared. (m/s 2 )

Section 2: Acceleration (pg. 291) Positive and Negative Acceleration When you speed up, your final speed always will be greater than your initial speed. So subtracting your initial speed from your final speed will give you a positive number. (see example on pg. 291) Ex: increase speed from 4 m/s to 6 m/s in 5 s. Use the Acceleration Equation: = 0.4 m/s When speed decreases (slows down), your final speed is less than your initial speed so subtracting initial speed from final speed will give you a negative number. Your acceleration is negative.

Section 2: Acceleration (pg. 292) Graphing Accelerated Motion On a speed-time graph, a line sloping upward represents increasing speed, a line sloping downward represents decreasing speed, and a horizontal line represents zero acceleration or constant speed.