CHAPTER 1 MOTION & MOMENTUM

Transcription

1 CHAPTER 1 MOTION & MOMENTUM

2 SECTION 1 WHAT IS MOTION?

3 All atter is constantly in MOTION Motion involves a CHANGE in position. An object changes position relative to a REFERENCE POINT. DISTANCE is the total length of the route an object travels when it oves. DISPLACEMENT includes direction of the stopping point fro the starting point.

4 DISTANCE D=10 eters A B Reference point When going fro point A to point B o2on occurred because you traveled A distance (10 eters) fro your Reference point (A).

5 DISPLACEMENT N B W E S D = 50 M D = 30 M A D = 40 M DISTANCE = 70 METERS (40M + 30M = 70M) DISPLACEMENT = 50 M northeast

6 ATTENTION!!! SPEED & VELOCITY ARE ALMOST THE SAME THING BOTH TELL YOU HOW FAST YOU ARE GOING ONLY DIFFERENCE SPEED MEANS HOW FAST VELOCITY MEANS HOW FAST + A DIRECTION

7 Velocity is the distance traveled divided by the tie taken to travel the distance + a direction VELOCITY = Forula: DISTANCE TIME Mr. B walked 10 across the roo (that way) in 5 s. Mr. B traveled at a speed of 2 /s. V = or d t v = v = s s That way That way

8 The units of speed are units of distance divided by units of tie V = velocity d = distance t = tie The SI (syste international) unit for velocity is eters per second (/s) or s

9 RULE IF VELOCITY DOESN T GIVE YOU A DIRECTION YOU DON T HAVE TO INCLUDE ONE. IF IT DOES THEN YOU MUST INCLUDE IT.

10 An object in otion can change VELOCITY any ties as it oves fro one point to another: Speeding up Slowing down CHANGING DIRECTION

11 Speed how fast an object travels AVERAGE speed is the total distance traveled divided by the total tie taken. INSTANTANEOUS speed is the object s speed at a particular oent in tie. CONSTANT speed occurs when an object travels at a steady rate with the sae instantaneous speed for soe period of tie

12 MOTION can be graphed on a distance-tie graph Tie plotted on the horizontal axis (x - axis) Distance plotted on the vertical axis (y - axis) 5 distance s 2s 3s 4s 5s 6s 2e

13 The steeper the line on a distance-tie graph, the GREATER the VELOCITY distance Much faster fast 1s 2s 3s 4s 5s 6s 2e

14 A horizontal line on a distance-tie graph indicates that no change in position is occurring and the VELOCITY is zero. distance s 2s 3s 4s 5s 6s 2e

15 Velocity is the speed of an object and its direction of otion. Velocity changes if either, or both of these change.

16 Speed vs. Velocity Speed is how fast an object is traveling Velocity is how fast an object is traveling and also the direction!!!

17 Section 2 Acceleration

18 Acceleration - change in velocity divided by the tie for the change to occur. Changes include: Speeding up Slowing down CHANGING DIRECTION Can be calculated if you know the object s velocity changed during a given tie period.

19 Forula ACCELERATION = (FINAL VELOCITY INITIAL VELOCITY) TIME a = (V f - V i ) t

20 The unit for acceleration is: Distance divided by tie squared The SI unit for acceleration is: Meters per second squared s 2

21 ADVANCED ONLY!!! PHYSICS BOOKS (WHEN YOU ARE IN 11 TH GRADE) refer to this as this forula: a = ΔV t Δ (greek letter delta) eans change in this is the equivalent to soething soething else.

22 Acceleration is POSITIVE when an object SPEEDS UP. Acceleration is NEGATIVE when an object SLOWS DOWN.

23 Exaple #1 A dog sat on the sidewalk. The dog saw his aster and ran at 4 eters per second in 2 seconds. What was the dog s acceleration? V i = 0 V f = 4 t = 2 s s s a = a = a = 4 (V f - V i ) s 2 s t (4 s - 0 ) 2s s a = 2 s 2

24 Exaple #2 A dog was walking at a Velocity of 4 eters per second west. The dog cae to a stop in 2 seconds. What was the dog s acceleration? V i = 4 s f = 0 t = 2 s s s west west a = a = a = - 4 (v f - V i ) s 2 s t (0 west s - 4 ) west 2s s west a =- 2 west s 2

25 Velocity - Tie graph Graphing acceleration: Velocity on vertical axis (y - axis) Tie on horizontal axis (x - axis)

26 An object speeding up will have an upward slope. velocity ( ) s s 2s 3s 4s 5s 6s 2e

27 An object slowing down has a downward slope. velocity ( ) s s 2s 3s 4s 5s 6s 2e

28 A horizontal line eans NO acceleration. Velocity ( ) s s 2s 3s 4s 5s 6s 2e

29 oentu Section 3

30 Mass - the aount of atter in the object. The SI unit for ass is kg. Weight of an object is related to its ass. A bowling ball has ore ass than a pillow and weighs ore. However the pillow is larger than a bowling ball. DO NOT LET SIZE OF AN OBJECT FOOL YOU!!!

31 Inertia - tendency of an object to resist a change in its otion. The ore ass an object has the harder it is to speed it up, slow it down, or turn it.

32 Moentu - a easure of how difficult it is to stop a oving object. Equals the product of ass and velocity

33 Moentu The sybol used to signify oentu is the letter p The equation is written as: p = v p - oentu - ass v - velocity

34 The SI unit for oentu is: kg. /s kilogras ultiplied by eters per second

35 Moentu Equation = 14 kg v = 2 p =? s north P = v P = (14 kg) x (2 P = 28 kg. s s north north)

36 Law of conservation of otion - states that the total oentu of objects that collide with each other is the sae before and after the collision.

37 Outside forces such as gravity and friction are alost always acting on objects during a collision. These forces are sall and can be ignored.

38 After Collisions Objects could stick together Collide and bounce off