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Linear Motion – Velocity / Acceleration What is velocity? What is constant velocity? If a car is traveling in a circle, is it maintaining constant velocity? What is changing velocity? What is acceleration? *Acceleration, like velocity is directional. If we change speed, direction, or both, we accelerate. Acceleration = change of velocity / time interval or Acceleration (along a straight line) = change of speed / time interval For Example: 300 km/h / 1 s = 300 km/h·s Note: The acceleration is 300 km/h·s Which is read as “300 kilometers per hour-second” What is deceleration? Problems: 1. Suppose a car moving in a straight line steadily increasing its speed each second, first from 35 to 40 km/h, then from 40 to 45 km/h, then from 45 to 50 km/h. What is its acceleration? 2. In 5 seconds a car moving in a straight line increases its speed from 50 km/h to 65 km/h, while a truck goes from rest to 15 km/h in a straight line. Which undergoes greater acceleration? What is the acceleration of each vehicle?