Ch. 2 Section 1 Motion

What is motion? Motion is when an object changes position. How do you know that the racecar moved? –It changed its position on the track.

How can you tell something has changed position? In order to see if something has changed position (motion) you need a reference point. –For example, the starting or finishing line of a racetrack.

What is distance? Easy question! Distance is how far an object has moved. We measure distance in METERS!

What is displacement? Suppose a runner jogs north to the 50-m mark and then turns around and runs back south 30-m. Total distance is 80-m. Two directions - north and south. Displacement is the distance and direction. Displacement is the difference between the joggers end point and the joggers beginning point. Displacement = 20 m

What is the difference between distance and displacement? Distance is how far something has moved. Displacement is how far something has moved from the starting point while considering the direction it moved!

What is speed? Speed is the distance an object travels over a certain amount of time. Any change over time is called a RATE. Speed is the rate at which distance is traveled.

SPEED FORMULA Speed = distance / time S = d / t

Speed Example Suppose you ran 2 km in 10 min. –What is your rate? S = d/t S= 2 km /10 min. S= 0.2 km/min. Remember the units!!!

Constant Speed… What does constant mean? If you are driving on the highway and you set your cruise control, you are driving at a constant speed. What would a constant speed graph look like?

Constant Speed Graph

Do you always go the same speed? No! Most of the time you are increasing speed, decreasing speed, or stopping completely! Think about driving a car or riding a bike!

What would a changing speed graph look like?

What is average speed? How do you find an average? Average speed is the total distance traveled over the total time Avg. Speed = Total d / Total t Avg S = Td/Tt

What is Instantaneous speed? What does a speedometer in a car do? –It shows how fast a car is going at one point in time or at one instant. Instantaneous speed is the speed at a given point in time.

What is Velocity? Speed is how fast something is moving. Velocity is how fast something is moving and in what direction it is moving. Why is this important? –Hurricanes –Airplanes

Speed or Velocity? If a car is going around a racetrack, its speed may be constant (the same), but its velocity is changing because it is changing direction.

Speed or Velocity? Escalators have the same speed (constant), but have different velocities because they are going in different directions.

Is it moving? Is the earth moving right now? –How do you know? How did the countries get where they are today? –How do you know?

Is it still moving? Are continents still moving? –How do you know?