Section 1: Describing and measuring Motion Chapter 1: Motion Section 1: Describing and measuring Motion

Observing Motion Motion- distance from another object is changing. Reference Point- object that is used for comparison to determine if something is in motion.

Draw a hot air balloon in motion and show how it has moved relative to a reference point.

Calculating Speed: Speed- the distance traveled by an object divided by the time taken to travel that distance.

Formula for Speed

The SI unit for speed include: meters per second (m/s) kilometers per second (km/s) feet per second (ft/s) miles per hour (mi/h) yards per second (y/s)

Average Speed Most of the time, objects do not move at a constant speed. Formula: Average speed = total distance total time

Instantaneous Speed: the rate at which an object is moving at a given instant in time. Example: Car speedometer

Let’s do some practice problems! Formula practice Average speed lab

Speed on a Graph Speed can be represented on a distance-time graph. x-axis = time y-axis = distance The slope of the line on a distance-time graph for speed represents the rate of speed.

Usain Bolt

Calculate Usain Bolt’s Average Speed Distance: 100 meter Time: 9.58 seconds Average Speed = 100m 9.58s Bolt’s Average Speed = 10.44m/s

Let’s do some practice - Motion in a line practice sheets

Velocity Example- an airplane traveling 600 km/h south. Velocity- is the speed of an object in a given direction. Speed and direction need to be constant Example- an airplane traveling 600 km/h south. Constant velocity is always motion along a straight line.

Chapter 1: Section 3 Acceleration Note: We skipped chapter 1: Section 2!

Acceleration Acceleration- the rate at which velocity changes over time. Remember: velocity involves both speed and direction. An object accelerates if it; 1) changes direction or, 2) changes speed

Types of Acceleration Acceleration is commonly associated with an increase in speed, but an object accelerates if it changes direction as well. Even if a car is moving at a constant speed its velocity changes when it makes a turn. positive acceleration- an increase in velocity (This is the same as speeding up in the positive direction or slowing down in the negative direction.) negative acceleration- a decrease in velocity (This is the same as slowing down in the positive direction or speeding up in the negative direction.)

Calculating Acceleration Acceleration = final velocity – initial velocity time Final = ending velocity Initial = starting velocity

Some common units for acceleration are: - meters per second per second (m/s/s or m/s2) - kilometers per hour per second (km/h/s)

As a roller coaster car starts down a slope, its speed is 4m/s As a roller coaster car starts down a slope, its speed is 4m/s. But 3 seconds later, at the bottom its speed is 22m/s. What is its average acceleration? Initial Speed: 4m/s Final Speed: 22m/s Time: 3s

Formula: A = final velocity – initial velocity time Substitution: 22m/s – 4m/s 3s Answer: 6m/s2

Let’s practice some acceleration problems

Graphing Acceleration Acceleration can be represented on a velocity- time or speed-time graph. x-axis = time y-axis = velocity or speed

Velocity-Time Graph

Velocity-Time Graph

Let’s look at some graphs