Motion Chapter 2

What is motion?

Describing Motion

Speed

How to use the Speed formula: SPEED= Distance Time TIME= Distance Speed DISTANCE= Speed x Time Solving for Speed Solving for Time Solving for Distance  What is the easiest way to remember these formulas without memorization? S D T

Let’s Practice  A windsurfer travelled 28 km in 1 hour 45 minutes. Calculate his speed.

How do we change time into a decimal? ¼ 0.25 ½ 0.50 ¾ 0.75

How do we change time into a decimal? 22/ / / /

How do we convert time to a different unit?

Let’s Practice  A windsurfer travelled Northwest 28 km in 1 hour 45 minutes. Calculate his speed. Speed = Distance Time Speed = _______ Speed =

Let’s Practice  A salesman travelled at an average speed of 50 km/hr towards Ohio for 2 hours and 8 mins. How far did he travel? Distance = Speed x Time Distance =

Let’s Practice  A train travelled from Nashville to Chicago, 470 miles, at an average of 60 mph. How long did the journey take? Time = Distance Speed Time = ______ Time =

Speed Velocity

So basically…

Acceleration

How to calculate Acceleration: ACCELERATION = velocity = change in velocitytime a = v f – v i t Change in velocity = final velocity – initial velocity ACCELERATION = final velocity – initial velocity time

Calculating + Acceleration: a = v f – v i t A jet airliner starts at rest at the end of a runway and reaches a speed of 80 m/s in 20 seconds. What is its acceleration? a = v f – v i t a = (80 m/s – 0 m/s) 20 s a = 80 m/s 20 s a = 4 m/s/s a = 4 m/s 2

Calculating - Acceleration: a = v f – v i t  Objects slow down A skateboarder is moving in a straight line at a constant speed of 3 m/s and comes to a stop in 2 seconds. What is his acceleration? a = v f – v i t a = (0 m/s – 3 m/s) 2 s a = -3 m/s 2 s a = -1.5 m/s/s a = -1.5 m/s 2