160 likes | 271 Views
Speed. Warm up. What 2 measurements do you need to know to find the speed of something? What is the difference between speed & velocity?. Warm up. What 2 measurements do you need to know to find the speed of something? Distance & time. Warm up.
E N D
Warm up • What 2 measurements do you need to know to find the speed of something? • What is the difference between speed & velocity?
Warm up • What 2 measurements do you need to know to find the speed of something? Distance & time
Warm up • What is the difference between speed & velocity? Speed is distance / time Velocity is speed & direction
A dog travels 20 meters and it takes 2.5 seconds. What is the dog’s speed? Speed = distance time 20 = 8 m/s 2.5
“Speed Machines” Worksheet Check your answers Be sure to find the speed in miles/hour
600 = 150 m/h 4 • 380 = 760 m/h .5
800 = 320 m/h 2.5 • 239 = 318.67 m/h .75
A. 2200 x 2 = 4400 miles • B. 2200 x 3 = 6600 miles • C. 2200 x 5 = 11,000 miles
Speed Activity Mrs. Pafundi ran 1 mile in 10.37 min. 1 mile__ 11 min .09 mile X 60 min 1 min 1 hr Step 1 = .09 mi/min How many miles/hr? = 5.4 mi/hr Step 2 5.4 mi X 1.609 km 1 hr 1 mi = 8.7 km/hr Step 3
Acceleration Acceleration – rate at which velocity (speed & direction) changes • Occurs when any of these happen: • Increase speed • example: • Decrease speed • (also called deceleration) • example: • Change direction • example:
Acceleration acceleration = final velocity – initial velocity time time example: An airplane starts and travels 40 m/s after 5 seconds. What is its acceleration? 40 m/s - 0 m/s = 40m/s = 8m/s/s = 8 m/s2 5s 5s
Set up the equation and then solve. Use your notes. • As a roller coaster starts down a slope, its • velocity is 4m/s. But 3 seconds later, its • velocity is 22m/s in the same direction. • What is its acceleration? • Initial velocity = • Final velocity = • Time = Warm-up 4 m/s 22 m/s 3 s 22 m/s - 4 m/s 3 s = 18 m/s 3 s = 6 m/s2
Set up the equation and then solve. Use your notes. • A falling raindrop accelerates from 10 m/s to • 30 m/s in 2 seconds. What is its acceleration? • Initial velocity = • Final velocity = • Time = Warm-up 10 m/s 30 m/s 2 s = 20 m/s 2 s 30 m/s - 10 m/s 2 s = 10 m/s2
Set up the equation and then solve. Use your notes. • A certain car can accelerate from rest to 27 m/s • in 9 seconds. What is its acceleration? • Initial velocity = • Final velocity = • Time = Warm-up 0 m/s 27 m/s 9 s = 27 m/s 9 s 27 m/s - 0 m/s 9 s = 3 m/s2