Acceleration Direction of Acceleration Describe the motion of
Acceleration
Direction of Acceleration Describe the motion of an object with vi and a as shown to the left. Vi a + + • Moving right as it speeds up + - • Moving right as it slows down - - - + • Moving left as it speeds up • Moving left as it slows down
Graphing Velocity • The slope (rise/run) of a velocity/time graph is the acceleration. – Rise is change in v – Run is change in t • This graph shows a constant acceleration. • Average speed is the midpoint.
Acceleration • Rate of change in velocity • What are the units? – SI Units: (m/s)/s or m/s 2 – Other Units: (km/h)/s or (mi/h)/s • Acceleration = 0 implies a constant velocity (or rest)
Displacement with constant acceleration ΔX = (1/2) (Vi + Vf)Δt
Displacement with Constant Acceleration Practice • A car accelerates uniformly from rest to a speed of 23. 7 km/h in 6. 5 s. Find the displacement the car travel during this time. • 21 m, forward
Velocity with constant acceleration Vf =Vi +aΔt
Displacement with constant acceleration ΔX = Vi Δt +(1/2) a (Δt)2
Displacement and Velocity with Constant Acceleration Practice • A car with an initial speed of 23. 7 km/h accelerates at a uniform rate of 0. 92 m/s 2 for 3. 6 s. Find the final speed and the displacement of the car during this time. • 9. 9 m/s and + 30 m forward
Final Velocity after any displacement
Displacement and Velocity with Constant Acceleration Practice • A car travelling initially at +7. 0 m/s accelerates at the rate of +0. 80 m/s 2 for a distance of 245 m. – A. What is its velocity at the end of the acceleration? • +21 m/s
Useful Equations 1. 2. 3. 4. 5.
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