1. Motion

2. Motion
a change in position, or location of a place or object, over a certain amount of time
relies on a frame of reference or something assumed to be stationary
is relative to a frame of reference
i.e. – you may be stationary as you sit in your seat, but you are moving 30 km/sec (≈19 mi/sec) relative to the Sun
Relative Motion Simulation

3. Speed the rate at which an object moves
a measure of how fast something moves, or the distance it moves, in a given amount of time
Formula:
typically expressed in units of m/s
is considered average when taking into account the total distance covered and the total time of travel
is considered constant when it does not change
is considered instantaneous when it represents a specific instant in time
S = d t
00:00. 4 5 3 1 2 6
What is the ball’s speed?
6 meters

4. Interesting Speeds meters/second miles/hour Cockroach Kangaroo Cheetah
1.25
2.8
Kangaroo 15 34
Cheetah 27 60
Sound
(in 200C air)
343
767
Space Shuttle
(getting into orbit)
7,823
17,500
Light
300,000,000
671,080,888

5. Practice Problems - Speed
If you walk for 1.5 hours and travel 7.5 km, what is your average speed?
2. Calculate the speed of a bee that flies 22 meters in 2 seconds.
S = d t
7.5 km
5 km hr
S = =
1.5 hr
22 m
11 m
sec
S = d t
S = =
2 sec

6. The Speed Triangle
S = d t
t = d S
d = S t . d d S t S . t

7. Distance-Time Graph Shows how speed relates to distance and time D50 40 30 20 10 60 70 80 90
100
Time (seconds)
120
Distance (meters) D
This distance-time graph will show a student’s speed as s/he returns to class after lunch.
What is the speed from C-D ?
What is the speed from B-C ? B C
What is the student’s average speed?
What is the speed from A-B ? A

8. Describe What’s Happening (distance-time graphs)
Constant speed; away from starting point
Constant speed; no movement
Constant speed; toward the starting point

9. Can you figure this out?
Two birds perched directly next to each other, leave the same tree at the same time. They both fly at 10 km/h for one hour, 15 km/h for 30 minutes, and 5 km/h for one hour. Why don’t they end up at the same destination?

10. Velocity the rate of change of an object’s position
speed in a given direction
is considered constant when speed and direction do not change
changes as speed or direction changes
is a vector
can be combined
Example
If you are walking at a rate of 1.5 m/s up the aisle of an airplane that is traveling north at a rate of 246 m/s, your velocity would actually be m/s north
10 m/s
Does the ball
have a constant
velocity?
What is the formula for calculating velocity?
29 m/s east
29 m/s west
visuals taken from:

11. Acceleration the rate at which velocity changes is a vector
occurs when something is speeding up (+), slowing down (-), or changing direction
Formula:
typically expressed in units of m/s2
is always changing when traveling in a circle - centripetal
10 m/s
Is the ball
accelerating?
a = vf – vi t
Describe the car’s acceleration
Describe the car’s acceleration
a = 0 m/s – 10 m/s = -5 m/s2
2 s
a = 50 m/s – 0 m/s = 10 m/s2
5 s

12. Understanding Acceleration
Time
(sec)
Velocity
(m/s) 1 2 3 4 5
When dropped, the ball will accelerate toward the center of the Earth at a rate of m/s2 because of gravity. What will be the ball’s velocity at each second?
9.8
19.6
29.4
39.2
49.0

13. Practice Problems - Acceleration
Tina starts riding her bike down a hill with a velocity of 2 m/s. After six seconds, her velocity is 14 m/s. What is Tina’s acceleration?
2. A motorcyclist goes from 35 m/s to 20 m/s in five seconds. What was his acceleration?
a = vf – vi t
14 m/s -
2m/s
2 m s2
a = =
6 s
a = vf – vi t
a =
20 m/s -
35 m/s
-3 m s2 =
5 s

14. Describe the student’s acceleration as she travels to class?
Velocity-Time Graph
Shows how acceleration relates to velocity and time 50 40 30 20 10 60 70 80 90
100
Time (seconds) 2 4 6 8 12
Velocity (meters/second)
This velocity-time graph will show a student’s acceleration as she returns to class after lunch.
Describe the student’s acceleration as she travels to class?

15. Describe What’s Happening (velocity-time graphs)
Constant, positive velocity; away from starting point
Constant, zero velocity
Constant, negative velocity toward the starting point
What do all of these velocity – time graphs have in common?
How do these relate to the distance – time graphs? D T D T D T

16. Applying What You Have Learned
Describe what’s happening in the graphs. How would it look on a distance-time graph? T D T D T

17. Momentum p = mv Formula: a measure of mass in motion is a vector
the product of an object’s mass and velocity
Formula:
typically expressed in units of kg·m/s
is in the same direction as the velocity
makes an object harder to stop or change direction as it increases
can be transferred
is conserved
p = mv
20 kg
Which object has more momentum – the curling rock or the hockey puck? Explain your reasoning.
Describe the scenario where the puck would have more momentum than the curling rock?
0.17 kg

18. Practice Problems - Momentum
What is the momentum of a 7.3 kg bowling ball moving at 8.9 m/s?
2. At a velocity of 8.5 m/s, Tim moves down a hill on an inner tube. If his mass is 59 kg, how much momentum does he have?
p = mv
p =
(7.3 kg)
(8.9 m/s) =
65 kg·m/s
p =
(59 kg)
(8.5 m/s)
p = mv =
502 kg·m/s

19. Frame of Reference (Reference Point)
a stationary location or object to which you compare other locations or objects
none are truly stationary relative to all others – what is not moving in one is moving in another
Task
Using your body as the frame of reference, describe your classmate’s motion as s/he walks to the classroom door. How does your frame of reference impact your description compared to that of others?
How does frame of reference explain why people thought the Earth was in the center of all celestial bodies?

20. Vector a quantity that has both direction and magnitude (size)
drawn as an arrow which shows direction and magnitude (length of arrow)
consists of two parts: tail and head
Head
Tail
Consider the vectors above. Describe the direction and relative magnitude (speed) of each car based on the vector.

21. Combining Vectors can be combined/added
What is the total velocity for each of the people/animals on the conveyor belt?
3 m/s
2 m/s
1 m/s
2 m/s
3 m/s
dog
belt
2 m/s
belt
ram
3 m/s
man’s total
velocity
2 m/s
belt
1 m/s
man
1 m/s
dog’s total
velocity
ram’s total
velocity = 0 m/s
2 m/s
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