1. MEASURING MOTION Chapter 11 Section 1

2. STANDARDS Standard 3 Motion: 1. Investigate the relationships among speed, position, time, velocity, and acceleration Embedded Mathematics: 1. understand the mathematical principles behind the science of physics 2. Utilize appropriate mathematical equations and processes to solve basic physics problems

3. OBJECTIVES 1.Explain how a frame of reference is related to motion 2.Distinguish between distance and displacement 3.Compare and contrast speed and velocity 4.Calculate the speed/velocity of an object when given the distance and time 5.Calculate the time an object takes to travel a distance when given the distance and speed/velocity of an object 6.Calculate the distance an object travels when given the time and speed of an object 7.Explain what the slope of a distance vs time graph represents

4. MOTION IS… Easy to detect How can you tell that there is something moving within these pictures? How can you tell that I am moving around the room? In order to detect motion… Observe the object in motion relative to stationary points Frame of reference or reference point What are some examples of frames of reference? Hint how would you explain to someone how to get to your house? Trees Houses Directions such as north, south, east, west, up, down, left, right Objective 1: Explain how a frame of reference is related to motion

5. MOTION UNMASKED Two things to help describe motion Frame of reference Distance or displacement How far an object moves Distance is not always the same thing as displacement!! WHAT?!? Distance is how far an object moves along a path Displacement is how far an object moves from the starting point What does this mean?!? Distance is not always a straight line, but displacement is! Objective 2: Distinguish between distance and displacement

6. THE NEED FOR SPEED!! Speed vs. Velocity Aren’t these the same thing? NO they are not! WHAT?!? Similarities Both measure how fast an object travels Both are calculated as distance/displacement divided by time The BIG difference Velocity includes DIRECTION! Summary… Speed tells how fast an object moves Velocity tells both the speed and direction of the object Objective 3: Compare and contrast speed and velocity

7. CALCULATING…... Speed/velocity!!! Must measure two quantities… Distance/displacement Measured in meters (m) Time Measured in seconds (s) Unit for speed is the meter per second (m/s) Types of speed Instantaneous speed = speed in an instant (one moment 50 mi/hr the next 70 mi/hr) Constant speed = equal distances in equal amounts of time (a constant 70 mi/hr) Average speed = the average of all the speeds within a certain amount of time When we calculate speed… We are calculating AVERAGE SPEED

8. STILL CALCULATING… Objective 4: Calculate the speed/velocity of an object To calculate velocity must have Distance/displacement Time DIRECTION!! Example: Find the velocity of a swimmer who swims 110 m toward the shore in 72 s. What are we given? 110 m and 72 s Direction is what? Objective 5: Calculate the time an object takes to travel a distance To calculate time must have Distance/displacement Speed or velocity Example: A baseball is thrown 38 m from first to third base at a velocity of 22.5 m/s. How long did the ball take to travel from 1 st to 3 rd base? What are we given? 38 m and 22.5 m/s Objective 6: Calculate the displacement an object travels To calculate distance must have Speed/velocity Time DIRECTION! Example: Calculate the displacement in kilometers that a cyclist would travel in 5.00 h at an average velocity of 12.0 km/hr southwest. What are we given? 5.00 hours and 12.0 km/hr What is the direction? v t d

9. GRAPHING MOTION!! When graphing motion Distance On the y-axis Time On the x-axis The Slope!! Calculating Rise over run The change in y over the change in x Equivalent to The object’s speed!! Objective 6: Explain what the slope of a distance vs time graph represents