1. Horizontal Motion Eqns

2. Average Velocity Revisited…
And… by definition of average

3. So…

4. Displacement depends on acceleration, initial velocity, and time…
Displacement = ½ * (initial vel. + final vel.)*(time)

5. Remember…

6. With uniform acceleration…
And since

7. In summary
Not derived…

8. You are designing an airport for small planes
You are designing an airport for small planes. One kind of airplane that might use this airfield must reach a speed before takeoff of at least 27.8 m/s, and can accelerate at 2m/s2. If the runway is 150m long, can this airplane reach the proper speed to take off? If so, provide evidence. If not, find the minimum length that the runway must have.

9. Suppose you want to design an air-bag system that can protect the driver in a head-on collision at a speed of 28m/s (approximately 60mph). Calculate how fast the air bag must inflate to effectively protect the driver. Assume the car crumples upon impact over a distance of about 1m.