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# Velocity

## on Nov 23, 2011

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## VelocityPresentation Transcript

• Velocity• The speed and direction of an object’s motion. –88 km / hr southwestImage source: http://www.myteacherpages.com/
• VELOCITYSPEED IN A GIVEN DIRECTION d V = t direction
• A bird flies south at 20 m/s.• SPEED = 20 m/s• VELOCITY = 20 m/s south
• A tropical disturbance spotted east of thePhilippines was moving at 60 km per hour ata Northwesterly direction and havingmaximum sustained winds of 150 km/h?What is the storm’s velocity?Given: S= 60km/h T= 10s dir= NW1.Formula V= d/t with dir2.Work/Answer V= 60km/h NW
• CONSTANT VELOCITY
• CHANGING VELOCITY
• COMBINING VELOCITIES How fast will this ball move? What factors may affect its speed?
• COMBINING VELOCITIES Rowing speed = 16 km/hr River speedV1(Boat) = 16 km/hr (downstream) =V2 (river) = 10 km/hr 10 km/hrCombined velocity: 26 km/hr
• What is the velocity if you aremoving upstream? Combined velocity: (V1) 16 km/hr – (V2) 10 km/hr = (CV) 6 km/hr
• Why is the idea of combining velocities important to launching rockets?
• 1. A runner moving eastward covers adistance of a 100 meters in 10 seconds.What is his velocity?Given: D= 100 m T= 10s dir= East1.Formula V= d/t with dir2.Work V= 100m/10s East3.Answer V= 10m/s East
• 3. Lisa is walking to a friend’s house. She walks 500m for 10minutes, then realizes she forgot something important tobring. She turns around, and hurries back to her house. Thewalk/jog back takes her 5 minutes.Given: Total D= 500m + 500m = 1,000m Total T= 10min + 5 min= 15 min T= 10 min D= 500m D= 500m T= 5 min
• 3. Lisa is walking to a friend’s house. She walks 500m for 10minutes, then realizes she forgot something important tobring. She turns around, and hurries back to her house. Thewalk/jog back takes her 5 minutes.a. What was her average speed in m/min?Given: Total D= 500m + 500m = 1,000m Total T= 10min + 5 min= 15min1.Formula Ave S = total D/total T2.Work Ave S = 1,000m/15min3.Answer Ave S = 67 m/min
• 4. Nelson is running around the track oval. The oval is 800m long. He is running at a constant speed. It takes him 180 s to complete the track and get back to where he started.a. What is Nelson’s speed in m/s? Given: d= 800 m t= 180 s running at constant speed
• a. What is Nelson’s speed in m/s?Given: d= 800 m t= 180 s running at constant speed1. Formula S= d/t2. Work V= 800m/180s around oval3. Answer V= 4.44 m/s around oval If Nelson is running at constant speed, is he also moving at constant velocity ? No, he is always changing direction (running around the oval).
• 3. Nemo is swimming his way to his best friend’s house Crush (the turtle). Nemo is swimming at 12 km/h and the current is moving at 10 km/hr.a. On the way to Crush’s house, he swims with the current. What is Nemo Nemo’s combined velocity on the way to Crush’s house? CurrentGiven: V1= 12km/h V2= 10 km/h dir= to Crush’s house (Nemo) (current)1.Formula CV= V1 + V22. Work CV= 12 km/h + 10 km/h3. Answer CV= 22 km/h to Crush’s house
• b. When Nemo leaves Crush’s to go home, he has to swim against the current. What is Nemo’s combined velocity on the way home?Given: V1= 12km/h V2= 10 km/h dir= Nemo’s home1.Formula CV= V1 - V22. Work CV= 12 km/h - 10 km/h3. Answer CV= 2 km/h on the way home