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What happens if the velocity changes?. Accelerated Motion (or Motion with Changing Velocity). Acceleration : the rate at which velocity is changing. The change may be in magnitude, direction, or both. The slope of the velocity is the acceleration. For constant acceleration:
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Accelerated Motion(or Motion with Changing Velocity) • Acceleration: the rate at which velocity is changing. The change may be in magnitude, direction, or both.
The slope of the velocity is the acceleration. • For constant acceleration: • In physics class, we will do numerical computations only with constant acceleration. Graphically, an object is accelerating if the graph of the velocity versus time is not linear.
Average and Instantaneous Velocity Average Velocity Instantaneous Velocity The velocity at a particular instant in time. For motion at constant velocity, the average velocity is the instantaneous velocity.
Average Velocity x t (t2,x2) (t1,x1) The secant line meets the curve at two points.
Instantaneous Velocity x t The tangent line meets the curve at one point. The instantaneous velocity is the velocity at a moment in time.
Graphs of Constant Acceleration constant x a v x a constant t t t t t v line line t parabola parabola Increasing velocity per unit time. a > 0 “Smiley face” a > 0 Decreasing velocity per unit time. a < 0 “Frowny face” a < 0
Equations of Motion No Acceleration Constant Acceleration
Sign Conventions y Object moves to the right but is slowing down. v > 0 x > 0 x a < 0 The sign of the quantity depends on whether it is pointing in the positive or negative direction. Displacement, velocity, and acceleration are vectors.