Physics Chapter 2 Motion in One Dimension

1. Physics Chapter 2Motion in One Dimension • I. Displacement & Velocity • A. Displacement: change in position • 1. displacement not equal to distance traveled • 2. displacement = change in position = final position – initial position = Δ x = xf - xi • 3. displacement can be positive or negative

2. B. Velocity: how fast something is moving • 1. Vavg = Δx • Δt • = change in position = displacement change in time time interval • 2. Not the same as speed, velocity has direction

3. 3. Velocity can be interpreted graphically • Slope = rise/run = change in vertical coord. change in horizontal coord. vavg. = Δx Δ t slope = average velocity

5. position time graph

6. Steeper slope = larger velocity position What does this graph mean? time

7. position Instantaneous velocity = tangent line of the slope time

8. II. Acceleration • A. Changes in Velocity • 1. Acceleration measures changes in velocity aavg = Δv/Δt = vf - vi tf - ti

9. 2. Acceleration has direction & magnitude If Δv is positive = acceleration is positive If Δv is negative = acceleration is negative When velocity is constant, acceleration is 0

11. 3. The slope and shape of a graph describes the objects motion velocity Time

14. B. Motion with Constant Acceleration • 1. Displacement depends on acceleration, initial velocity & time. vavg =Δx/ Δt vavg =vi +vf 2 therefore Δx/ Δt =vi +vf 2

15. 2. Displacement with Constant Acceleration • Δ x = ½ (vi + vf) Δt

16. 3. Final velocity depends on initial velocity, acceleration & time • vf = vi + aΔt Displacement with Constant Accl. Δx =vi Δt +1/2a(Δt )2

17. 4. Time can be found from displacement & velocities • Δt = 2 Δx vi +vf Final velocity after any displacement Vf2 =vi2 +2aΔx

18. III. Falling Object • A. Free Fall • 1. Free falling bodies undergo • constant acceleration • 9.81m/s2