Motion

1. What is motion? A way of describing how fast something is moving

2. What is a reference point? A point motion is measured against Usually a stationary object

3. How do you know if an object is in motion? An object is in motion if it changes position relative to a reference point

it depends on your reference point! Are you in motion? it depends on your reference point! 2 minutes

5. What is speed? The distance an object travels per unit of time. miles per hour miles/hour

6. How do you calculate speed? Divide the distance the object traveled by the amount of time it takes to travel that distance.

…some useful speeds Growing fingernails = 4 cm/year Walking speed = 3 miles/hr or 1.3 m/s Driving speed = 60 miles/hr or 26 m/s Earth’s revolution = 30 km/s Speed of light = 300,000 km/s

S = 60 miles/hour Example: 120 miles in 2 hours S = D T S = 120 miles Road Trip! Example: 120 miles in 2 hours S = D T S = 120 miles 2 hours S = 60 miles/hour

7. Why would you calculate average speed? Because most moving objects do not move at a constant speed. Think about biking uphill and downhill

…or think of traffic

8. How do you calculate average speed? Average speed = Total Distance Traveled Total Time of Travel

Traffic! = 15 km/hr Example: 32 km for 2 hours, then 13 km for 1 hour Total distance = 32 km + 13 km = 45 km Total time = 2 h + 1 hr = 3 hr Average speed = 45 km ÷ 3 hr = 15 km/hr

10. What is velocity? Speed in a given direction Ex: 20 miles/hour West A storm is moving 25 km/h. Should you prepare?

11. How can you describe changes in velocity? Change in velocity may be due to change in speed, change in direction, or both!

12. How do you graph speed? By a distance versus time graph! X-axis = time Y-axis = distance Slope = slant of line y Distance (m) 50 X 5 Time (min)

13. How can you interpret graphs of distance versus time? The slope represents speed Slope = slant of line = speed! Steep = Fast! Shallow = Slow!

What if it is flat? Flat = not moving!