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.

Motion

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

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

6 meters

00:00.0123456

What is the ball’s speed?

Interesting Speeds

meters/second miles/hour

Cockroach 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

Practice Problems - Speed1. 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

S = d t

S =

=7.5 km1.5 hr

5 km hr

S =

22 m2 sec

= 11 m sec

The Speed Triangle

.S

S = d t

t

t = d S

d

d = S t.

S t

d

Distance-Time GraphShows how speed relates to distance and time

0 5040302010 60 70 80 90 100Time (seconds)

20

40

60

80

100

120

Dis

tance

(m

ete

rs)

B C

DThis distance-time graph will show a student’s speed as s/he returns to class after

lunch.

What is the speed from A-B ?

What is the speed from B-C ?

What is the speed from C-D ?

What is the student’s average speed?

A

Describe What’s Happening(distance-time graphs)

Constant speed; away from starting

point

Constant speed; no movement

Constant speed; toward the starting

point

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?

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 247.5 m/s north

visuals taken from: http://www.amazing-animations.com/

29 m/s east

29 m/s west

10 m/s

10 m/s

Does the ballhave a constant

velocity?

What is the formula for calculating velocity?

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

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

10 m/s

10 m/s

Is the ballaccelerating?

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 9.8 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

Practice Problems - Acceleration

1. 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 =

=14 m/s - 6 s

2 m s2

a =

20 m/s -5 s

=-3 m s2

a = vf – vi

t

a = vf – vi

t

2m/s

35 m/s

Velocity-Time GraphShows how acceleration relates to velocity and time

0 5040302010 60 70 80 90 100Time (seconds)

2

4

6

8

10

12

Velo

city

(m

ete

rs/s

eco

nd)

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?

Describe What’s Happening (velocity-time graphs)

Constant, positive velocity; away from

starting point

Constant, zero velocity Constant, negative velocity toward the

starting point

How do these relate to the distance – time graphs?

D

T

What do all of these velocity – time graphs have in common?

D

T

D

T

Applying What You Have Learned

V

T

D

T

D

T

V

TDescribe what’s

happening in the graphs. How would it

look on a distance-time

graph?

Momentum 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.0.17 kg

Describe the scenario where the puck would have more

momentum than the curling rock?

Practice Problems - Momentum1. 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 = mv

p = =(7.3 kg)(8.9 m/s) 65 kg·m/s

p =

(59 kg)(8.5 m/s)= 502 kg·m/s

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?

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

Tail

Head

Consider the vectors above. Describe the direction and relative magnitude (speed) of each car based on the

vector.

Combining Vectors

can be combined/added

Image taken from: https://mholborn.sharepoint.com/sitepages/animated%20gifs.aspx

2 m/s

1 m/s

2 m/s

belt

1 m/s

man3 m/s

man’s total velocity

2 m/s

2 m/s

belt ram2 m/sram’s total

velocity = 0 m/s

3 m/s

2 m/s 3 m/s

dogbelt1 m/s

dog’s total velocity

What is the total velocity for each of the people/animals on

the conveyor belt?