How Scientists Record and Plot Motion Data Graphing Motion How Scientists Record and Plot Motion Data

Notes Write down the words in yellow. The words in white are discussion points, you may write these down, but are not required.

Important Vocabulary Data – pieces of information including words & numbers Data Table – a chart made up of columns and rows, used to organize data

Important Vocabulary Line Graph – graph that shows data as a line on a grid. Can show changes over time. X-axis – graphs horizontal line Y-axis – graphs vertical line

Distance-Time Graphs Scientists use line graphs to show the motion of an object. These line graphs are called distance-time graphs; they show the relationship between distance and time. X-axis = time an object travels Y-axis = distance an object travels

Types of Graphs Suppose a scientist measures how far a cheetah has run after a certain amount of time. The scientist records the data in the table below. Cheetah’s Motion Time (seconds) Distance (meters) 10 100 15 150 20 200 25 250 30 300

The scientist makes a line graph to show the cheetah’s motion. Types of Graphs The scientist makes a line graph to show the cheetah’s motion. Distance-Time Graph for Cheetah 500 400 300 200 100 Distance (meters) Cheetah 10 20 30 Time (seconds)

Constant Speed Graph Straight line – the speed did not change (remained constant for the time measured) Distance-Time Graph for Cheetah 500 400 300 200 100 Distance (meters) Cheetah 10 20 30 Time (seconds)

Constant Speed Graph To find the cheetah’s speed, divide the total distance by the total time. Speed = Distance/Time = 300 m/30 sec = 10 meters per sec The cheetah moved 10 meters during every second it was running. Distance-Time Graph for Cheetah 500 400 300 200 100 Distance (meters) Cheetah 10 20 30 Time (seconds)

Stopped Motion Graph A flat line on a d-t graph = shows an object has stopped moving. Distance-Time Graph for Cheetah 500 400 300 200 100 Distance (meters) Cheetah 10 20 30 40 Time (seconds)

Stopped Motion Graph Distance-Time Graph for Cheetah 500 400 300 200 100 Suppose after 30 sec the cheetah stops moving. After another 10 sec, at 40 sec, the distance traveled is 300 m. The graph shows that the cheetah had stopped moving. Distance (meters) Cheetah 10 20 30 40 Time (seconds)

Graphing Faster Motion A steeper line on a d-t graph = a faster, or greater, speed. Distance-Time Graph for Cheetah 500 400 300 200 100 Distance (meters) Cheetah 10 20 30 40 50 Time (seconds)

Graphing Faster Motion Now suppose after 40 sec, the cheetah starts moving again. It travels 200 m in the next 10 sec. The new part of the graph is steeper. It shows that the cheetah moved 200 m in 10 seconds. The cheetah moved faster than it did for the first 30 sec. Distance-Time Graph for Cheetah 500 400 300 200 100 Distance (meters) Cheetah 10 20 30 40 50 Time (seconds)

Let’s Practice What does the x-axis show? During which period of time did the cat stop moving? Ex: 0-30 sec During which period of time did the cat move faster? Distance Cat Travels over Time 100 90 80 70 60 50 40 30 20 10 Distance (meters) 20 40 60 80 100 Time (seconds)

Exit Ticket What is speed? How is it calculated? Find the speed of this object: Distance: 525 cm, Time: 3 seconds What does a flat, straight line on a Distance/Time graph mean?

Practice Motion Graphs information sheet and practice. http://camillasenior.homestead.com/motion_graphs.pdf