MOTION IN 1-DIMENSION

Vocab(Leave room for definitions)

Position (x) Displacement (∆x)= (xf -xi) Distance (d)

Delta (Δ) – The symbol used to define changeFinal – Initial

Is the pen moving?

Vocab (cont.)

Reference Point Reference Frame Veloctiy (v) Speed (s) At Rest

What is the difference between speed and Velocity?

Scalar vs. Vector

A scalar is a quantity with only magnitude.Magnitude = Size

A vector is a quantity with both magnitude and direction.

Speed is a scalar and Velocity is a vector. How does this make them different?

Speed – Distance over time (Scalar) Instantaneous

Velocity – The rate of change in position displacement over time

v = velocityx = positiont = time

t

ds

t

xv

_

t

xxv if

_

1. What is the van’s position at 10 sec? at 40 sec?2. At what position does the van start?3. What is the distance traveled between 40-50 sec?4. What is the displacement between 40-50 sec?5. What is the distance traveled between 0-70 sec?6. What is the displacement between 0-70 sec?

1. When is the van moving forward?2. When is the van moving backwards?3. When is the van at rest?4. When is the van traveling the fastest?

1. Make a table of time and position for every 10 seconds.2. Find the slope for each 10 second interval starting with 0- 10 sec.

time (sec) position (m)time (sec) position (m)

0 5

10 5

20 10

30 12.5

40 15

50 -5

60 -5

70 0

time (sec) position (m)

0-10 0

10-20 .5

20-30

30-40

40-50

50-60

60-70

1. Make a graph of this table.

time (sec) position (m)

0-10 0

10-20 0.5

20-30 0.25

30-40 0.25

40-50 -2

50-60 0

60-70 0.5

0 10 20 30 40 50 60 70 80

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

slope

slope

0 10 20 30 40 50 60 70 80

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

velocity vs. time

slope

time (sec)

Vel

oci

ty (

m/s

)

Average Speed/Velocity

Avg. speed=Total distance over total time.

...)(

...)(

321

321_

ttt

ddds

Practice problems

1. A person runs 2 m/s for 1 min and then 8 m/s for one min. What is her average speed?

2. A car travels 50 km in one hour and 100 km in one hour. What is the average speed in km/hr?

3. A cyclist rides 5.00 m/s for 2000. meters and then 15.0 m/s for 2000. meters. What is the cyclists average speed in m/s?

4. A horse runs 1000. meters at 20.0 m/s west. How fast must the horse run east for 1000. meters to make his average speed 40.0 m/s?

What is velocity? (What is it actually telling you)

How does this relate to the units of velocity? What do they mean?m/s , mi/hr , km/hr

Now describe 35 m/s. How about 65 mi/hr

More examples (don’t forget to leave room for your work)

1. If a mouse scurries 1.5 m/s for 2.00 min, how far has the mouse scurried?

2. If the same mouse scurries 3.5 m/s, how long (sec) will it take her to travel 1.00km?

How many minutes is this?

3. If a cat has only 2.00 min to travel 0.75 km to catch the mouse, how fast must the cat run in m/s?