1. Motion

2. An object is in motion if its distance from another object is changing, or it changes position relative to a reference point.

3. Motion A reference point is a fixed point used to determine motion. We are in motion according to what point? The tree? The house? The sun?The center of the Milky Way?

4. Measuring Motion International System of Units (SI) – a common measurement system allowing scientists to communicate accurately. We call this the metric system. The SI unit of distance is the meter. A soccer field is about 100 meters in length.

5. Measuring Motion Speed – the rate at which something covers a distance, or, the distance an object moves in a certain amount of time For example:  meters per second – m/sec  miles per hour – mi/hr  kilometers per hour – km/hr

6. Formulas:Speed = Distance / Time, or S= d / t So, if a car goes 2000 meters in 32 seconds, its speed is 2000 m/32 seconds, or 62.5 m/s (or 139.8 mph!) or, d = s x t or, t = d / s

7. Measuring Motion Average speed – the total distance traveled divided by the total time it takes. Instantaneous speed – the rate at which an object is moving at a given instant in time Velocity – tells the speed and the direction of the motion. For example: 50 km/hr due East

8. Acceleration Acceleration – the rate of change in velocity. In science, it refers to:  increasing speed – speeding up  decreasing speed – slowing down  changing direction – running in a circle To determine acceleration, you must calculate the change in speed per unit of time.

9. Acceleration The formula for acceleration is: Acceleration = Change in Velocity / Time OR a =    v t The triangle (  ) in the equation is the Greek symbol “Delta” which means change.

10. Acceleration Example: A plane taking off goes from 0 m/s to 40 m/s in 5 seconds before it takes off. To calculate its acceleration: Acceleration = 40 m/s – 0 m/s =8 m/s 2 5 sec The units for acceleration are “meters per second squared” OR m/s 2

11. Acceleration Due to Gravity When objects are dropped and accelerate due to gravity, their acceleration is 9.8 m/sec 2. What?! Do you mean that all objects will fall at the same rate?