Zusammenfassung der Ressource
MOTION
- Describing Motion?
- Motion: An object is in motion if its distance from another object is changing
- Reference Point(s): A place or object used for comparison to determine if something is in motion
- An object is in motion if it changes position relative to a reference point
- Stationary Objects (Tree, sign, building), make good reference points
- If a passenger is moving relative to a tree, it's concluded that the train is in motion
- Relative Motion
- "Calculation of the motion of an object with regard to some other moving object."
- Measuring Distance
- We use units of measurement to describe motion precisely
- International System of Units, In French: System International (SI)
- Scientists all over the world need to use the same unit of measurement in order to communicate clearly
- Meter: A unit of measurement
- Use SI units to describe quantities other than length
- Speed?
- Calculating Speed
- A measurement of distance can tell you how far an object travels
- If you know the distance an object travels in a certain amount of time, you can calculate the speed of the object.
- Speed: A type of rate
- Rate tells the amount of something that occurs or changes in one unit of time
- Speed of an object is the distance the object travels per unit of time
- Speed Equation
- Speed = Distance/Time
- To calculate the speed of an object, divide the distance the object travels by the amount of time it takes to travel that distance
- Average Speed
- To calculate average speed, divide the total distance traveled by the total time
- Instantaneous Speed
- The rate at which an object is moving at a given instant in time
- Velocity?
- Knowing the speed at which something travels doesn't tell everything about motion
- To describe an objects motion completely, you need to know the direction of motion
- Velocity: Speed in a given direction
- When you know both the speed and direction of an object's motion, you know the velocity of the object
- Graphing Motion?
- You can show the motion of an object on a line graph in which you plot distance versus time
- Slope: Steepness of a line on a graph
- Slope tells how fast a variable changes in relation to another variable
- The steeper the slope, the greater the speed.
- Constant slope represents motion at a constant speed
- Slope = Rise/Run
- Calculating Slope
- You can calculate slope of a line by dividing the rise by run
- Slope = Rise/Run
- Different Slopes
- Most moving objects don't travel at a constant speed
- Acceleration?
- Acceleration: The rate at which velocity changes
- In science, acceleration refers to increasing speed, or changing direction
- Increasing Speed: When an object's speed increases, the object accelerates
- Decreasing Speed: When an object's speed decreases, the object slows down
- Changing Direction: An object that is accelerating, but changing speed
- To determine acceleration of an object moving in a straight line, you must calculate the change in speed per unit of time
- Acceleration = Final Speed - Initial Speed/Time
- You can use both a speed-versus-time graph and a distance-versus-time graph to analyze the motion of an accelerating object.