2. How do you know you are moving?<br />use a reference point = place/object used for comparison<br />you are moving when your position relative to reference point changes<br />Good reference point: stationary object – it doesn’t move in relation to the Earth<br />You might be moving or not at the same time!!! It depends on the reference point you use. Can you think of an example of it?<br />
3. Average Speed<br />how fast you go in a period of time <br />rate = the amount of something that changes /occurs in a certain amount of time<br />speed (m/s) = distance (m/km) <br /> time (s/h)<br />Unit: m/s or km/h<br />
4. Practice<br />A cyclist travels 30km in 3 hours. What is his average speed?<br />An ant moves 5 cm in 2 seconds. What is its average speed?<br />The fastest car in the world, the SSC Ultimate Aero, would be able to travel 1505 km in 3.5 hours. What is its average speed?<br />http://br.youtube.com/watch?v=b5zqKWZ-38E<br />Curious facts:<br />Top speed of a human = 40 km/h<br />Fastest dog – greyhound = 64 km/h<br />Fastest fish – sailfish = 109 km/h<br />Fastest bird – peregrine falcon = 439 km/h<br />Fastest land animal = cheetah 112 km/h<br />
5. Average Speed x Instant Speed<br />Speed is not usually constant = average<br />Do you travel at the same speed the whole time you are driving from your house to the school?<br />Practice:<br />A cyclist travels 32km during the first 2 hours then 13km during the next hour. What is his average speed?<br />
6. Displacement<br />Minimal distance between 2 points<br />Two towns: A and B 10 km apart <br />Joined by a railway line that is straight, and goes through the hill in a tunnel <br />Joined by a road that goes around the hill – length= 25 km<br />Distance x displacement<br />Distance = 25 km<br />Displacement = 10 km east<br />What happens if you go from A to B and back again?<br />
7. Velocity<br />What happens when you hear someone saying a storm is traveling at a speed of 25km/h. Should you prepare for it?<br />It depends on the direction!<br />speed + direction = VELOCITY<br />You can say: the storm is moving 25km/h eastward.<br />Why is it important to know the velocity of certain objects?<br />Air traffic controllers must keep track of airplanes. Speed and direction are important!!!<br />
8. Graphing Speed<br />The steepness = SLOPE = tells you how fast something changes in relation to the other variable<br />The steeper the slope, the greater the speed<br />SLOPE = rise or (y2 – y1)<br /> run (x2 – x1)<br />
9. Interpret the Graph<br />
10. Interpret the Graph<br />B<br />C<br />A<br />E<br />D<br />
11. Acceleration<br />Motion doesn’t usually stay the same the whole time. <br />Imagine a soccer game: the player kicks the ball. The ball speeds up and slows down as it travels away from him until it stops.<br />When it speeds up = accelerate<br />When it slows down = decelerates/negative acceleration<br />Acceleration = rate at which velocity changes<br />
12. What happens with the speed?<br />
13. Calculating Acceleration<br />A = final speed – initial speed<br /> time<br />Unit: m/s2 or m/s/s<br />An airplane is taking off from Guarulhos Airport. It takes 5 seconds for the airplane to reach the speed of 40 m/s. <br /> Calculate the airplane’s acceleration.<br />