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Chapter 11: Motion. Section 11.3 Acceleration. Acceleration. The rate at which velocity changes is acceleration. Acceleration can be described as: Change in speed Change in direction Change in both Acceleration is a vector. The SI unit for acceleration is m/s 2 .
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Chapter 11: Motion Section 11.3 Acceleration
Acceleration • The rate at which velocity changes is acceleration. • Acceleration can be described as: • Change in speed • Change in direction • Change in both • Acceleration is a vector. • The SI unit for acceleration is m/s2. • Constant acceleration is a steady change in velocity. (Think of an airplane taking off.)
Calculating Acceleration • For objects moving in a straight line acceleration can be found using the following formula: Acceleration = change in velocity Total time OR Acceleration = (vf - vi) t
More Calculations • Acceleration can be positive or negative. (Think about speeding up or slowing down.) • Solve: • A car traveling at 10 m/s starts to decelerate steadily. It comes to a complete stop in 20 seconds. What is its acceleration?
Graphs of Accelerated Motion • The slope of a speed-time graph is acceleration. • Constant acceleration is shown by a linear graph. • If the slope is positive, the acceleration is positive. • If the slope is negative, the acceleration is negative.