1. 9/6 Vector Components  Text sections and 1.6-8  HW “9/6 2-D Vector Components” due Wednesday 9/11 On web or in 213 Witmer for copying

2. Concepts so far- Displacement,  x (distance moved) Instantaneous Velocity, v (at a particular time) Average Velocity, v ave (average over time) Change in Velocity,  v (speeding up or slowing down) Acceleration, a (how much the velocity changes each second)

3. Problem: An object goes from a velocity of 15 m/s right to 6 m/s right in 3 seconds. Find the acceleration, both its size (magnitude) and its direction, (left or right). How do the directions of the velocity and acceleration compare? What is the object doing during these 3 seconds? How far did the object travel during these three seconds? Hint: What is the average velocity? What will the objects velocity be in three more seconds if the acceleration stays the same?

4. Problem: A bullet exits a rifle at 85m/s. The barrel is 0.75m long. What is the acceleration of the bullet? Don’t use text equations, just the relationships between displacement, time, velocity and acceleration

5. Find the Displacement v (m/s) t (s) How far did the object go in 9 seconds? 10 What is the average velocity? 7 m/s Displacement = 63 m There are 31.5 shaded squares each representing 2 m of displacement. 2 x 31.5 = 63 Note that the displacement is the same as the shaded area.

6. Find the Displacement v (m/s) t (s) At what time is the object back where it started from? 10 What is its velocity at this time? If it returns to its starting point it must turn around. At what time does it do that? -10 10s 6s -8m/s What is the displacement from 2s to 13s? How many meters were put on the odometer from 2s to 13s?

7. Finding x and y Components v y = ? v x = ? v = 3.8 m/s  = 21° below horizontal  Opposite from , use Sin Adjacent to , use Cosine v y = 3.8 Sin 21 = 1.4m/s v x = 3.8 Cos 21 = 3.5m/s Make sure your calculator is set to degrees!

8. Finding x and y Components v y = ? v x = ? v = 15 m/s  = 35° v y = 15 Cos 35 = 12.3m/s v x = 15 Sin 35 = 8.6m/s