1. Chapter 11 – Part 1 Non-accelerated Motion Chapter 11.1-11.2
Physical Science
Chapter 11 – Part 1
Non-accelerated Motion
Chapter

2. Frame of Reference
A system of objects that are not moving with respect to one another
A reference point or system
BASICALLY …. Something unchanging to measure things from
Good frames of reference for measuring the motion of a car…
The Earth, the road, buildings, trees
Bad frames of reference for measuring the motion of a car….
Clouds, other cars on the road, bikers, flying birds

3. Relative Motion Movement in relation to a frame of reference
All Motion is Relative
This means… all motion is based on someone’s or something’s perspective
Examples
School busses
Cars on highway
LabQuest

4. Relative Motion
Or a more recent example

5. Measuring Distance Length of a path between two points
When an object moves in a straight line, the distance is the length of a line connecting the starting point and the ending point
SI Unit – meters
Other options- km, mi, cm

6. Displacement Distance with a direction How much an object is displaced
Distance – 5 kilometers
Displacement – 5 Kilometers North
How much an object is displaced
When objects travel in a straight line the magnitude (amount) of the displacement is equal to the distance travelled
When an object does not travel in a straight line, distance and displacement will be different

8. Vectors Scalar Quantities Vector Quantities 3 km + 3 km = 6 km
Have magnitude and direction
Scalar Quantities
Only have magnitude
Vector quantities can be represented with arrows of a scaled length
Length shows magnitude
Arrow shows direction
3 km
3 km
3 km + 3 km = 6 km

9. Vectors & Scalars Scalars- Have only Magnitude Vectors-
Have Magnitude & Direction
Scalars-
Have only Magnitude
Examples
Displacement
Distance
Velocity
Speed
Acceleration
Mass
Force
Time

10. Displacement in a straight line
4 km
7 km
4 km + 7 km = 11 km
8 km
5 km
8 km - 5 km = 3 km

11. Displacement that isn’t on a straight Path
Resultant Vector (red) – vector sum of 2 or more vectors
3 km
5 km
2 km
Finding Distance Using Scalar Addition = 7 km
Finding Displacement using Vector Addition = 5 km NE
1 km
1 km

12. These two vectors have the same ________________ and opposite ________________.

13. These two vectors have different ________________ but the same ________________.

14. These two vectors have the same ________________ AND the same ________________.

15. average Speed
Average Speed is equal to distance divided by time
𝑣 𝑎𝑣𝑔 = 𝑑 𝑡
How fast or slow something is going
A rate of motion

16. Instantaneous Speed Speed at a given moment of time
What the speedometer on a car reads

17. Constant Speed When speed is not changing
Instantaneous speed is equal to average speed at all times
NOT Speeding up or slowing down
Only ways to change speed is to speed up or slow down

18. Average Speed Constant Speed Instantaneous Speed
The Average speed over some time
Maintaining the same speed all the time
Speed of an object at a particular moment in time

19. Velocity Speed AND direction that an object is moving Vector Quantity
+ or – sign indicates which direction the velocity is
+ means North, Up, East, or to the Right
- means South, Down, West, or to the left
Sometimes multiple velocities can affect an objects motion
Sailboat, airplanes
These velocities combine with Vector Addition

20. Speed vs. Velocity Speed – tells how fast something is moving
Ex km/hr
Velocity – tells how fast something is moving and its direction
Ex. 35 mph North
Can an object move with constant speed but have a changing velocity?
Can an object move with constant velocity but have a changing speed?

21. 2 ways to change Speed
3 ways to change Velocity
Speed Up
Slow Down
Change Direction

22. acceleration Acceleration – The rate at which velocity changes
Can be described as ….
Changes in Speed
Changes in Direction
OR change in both Speed and Direction
Vector Quantity
Units are meters per second per second or m/s2

23. 3 Way to Accelerate
Speed Up
Slow Down
Change Direction

24. Can an object moving with constant speed be accelerating?

25. Devices in Cars that lead to acceleration

26. Calculating Acceleration
𝑎= 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒 = ∆𝑣 𝑡 = 𝑣 𝑓 − 𝑣 𝑖 𝑡
Divide the change in velocity by total time

27. Example
A car starts from rest and increases its speed to 25 m/s over the course of 10 seconds. What is the car’s acceleration?
𝑎= 𝑣 𝑓 − 𝑣 𝑖 𝑡 𝑣 𝑖 =0 𝑚 𝑠 𝑣 𝑓 =25 𝑚 𝑠 𝑡=10 𝑠𝑒𝑐
𝑎= (25 𝑚 𝑠 − 𝑚 𝑠 ) 10 𝑠𝑒𝑐 =2.5 m 𝑠 2

28. 𝒂= 𝒗 𝒇 − 𝒗 𝒊 𝒕 𝒗 𝒊 =𝟏𝟎 𝒎 𝒔 𝒗 𝒇 =𝟑𝟐 𝒎 𝒔 𝒕=𝟑 𝒔𝒆𝒄
𝑎= (32 𝑚 𝑠 − 𝑚 𝑠 ) 3 𝑠𝑒𝑐 =7.33 m 𝑠 2

31. Graphs of motion Motion can also be depicted very well using graphs
Two types of graphs
Displacement vs. time (D-t) graphs
Velocity vs. time (V-t) graphs
Straight,upward line on a V-t graph means constant acceleration
Straight,upward line on D-t graph means constant velocity
Displacement (m)

32. D-t graph of constant ‘v’
Displacement increases at regular intervals, so constant velocity
Graph below Increases displacement by 5 meters every sec.
To find vel. on a disp.- time graph, find Slope

33. Slope 5 m/s Rise/run=slope= 25/5 = Rise = 25 Run = 5
Tells the rate of increase of the y-value as you move across the x values for any graph
Slope = rise / run
In other words… how much the graph goes up divided by how much the graph goes across
Slope tells us properties of the motion being depicted
On a displacement time graph  slope = velocity
On a velocity-time graph  slope = acceleration
Rise/run=slope= 25/5 =
5 m/s
Rise = 25
If you took slope of smaller sections of the graph you would get the same answer since ‘v’ is constant
Run = 5

38. Velocity- Time graphs
v v. t graphs may look the same as some D v. t graphs, but the motion they describe can be very different because they deal with velocity, not distance.
**The slope, of a Velocity v. Time graph indicates Acceleration**.

40. Distance-time graph of changing velocity
Time (s)
Displacement (m) 1 8 2 11 3 18 4 15 5 25
What is v for 0-1 sec.??
What is v for 0-2 sec.??
What is v for 3-5 sec.??
What is v for 0-5 sec. ??

41. Distance-time graph of constant acceleration
Parabola….. If + acc, line keeps getting steeper and steeper d t

42. Avg. velocity from 0-1 sec. ? 4 m/s
Avg. vel. From 3-4 sec? 16.5
Acc. From 2-3 sec? 7 m/s2

43. Velocity vs. Time graph of constant acceleration
Velocity (m/s)

44. Position –time Graph Slope = rise/run … Rise = Run = Rise/run = 50 5
10 m/s = speed
Speed-time graph
Slope = rise/run …
Rise = 16
Run = 4
Rise/run =
4 m/s = acceleration

45. Free Fall Acceleration
As objects fall toward the Earth they are accelerating at a rate of 9.8 m/s2 downward
We can usually round 9.8 m/s2 to 10 m/s2
Objects in free fall will gain 10 m/s of speed for every 1 second it is falling
Time (sec)
Instantaneous Speed (m/s)
Acceleration (m/s2) 10 1 2 20 3 30 4 40

46. Free Fall Acceleration
Object is in free-fall any time it is ONLY under the influence of gravity
Including when something is thrown upwards
All objects (regardless of mass) fall at the same rate on Earth, when air resistance is ignored
Ball thrown upward with initial velocity of +30 m/s
Time (sec)
Instantaneous Vel. (m/s)
Acceleration (m/s2)
+30
-10 1
+20 2
+10 3 4 5
-20 6
-30