Measuring Motion 2013

7/29/2019 Measuring Motion 2013

1/15

Click to edit Master subtitle style

Measuring

Motion

All kinds of motion!!


2/15

What is

Motion? Motion is defined as an objectthat changes its position (or

travels some distance) in acertain amount of time.

Example: The car travels fromUptown to EWMS in 7minutes.


3/15

OK, but how do you know an

object has changed position? The change of position (or location) of an

object can be determined when compared to

a REFERENCE POINT. A REFERENCE POINT is another object

that is assumed not to be moving that can beused to compare the objects motion.

Examples: a tree, a building, starting point,finish line.


4/15

What is

Motion?Motion isANY OBJECT CHANGING ITSPOSITION IN A CERTAIN

AMOUNT OF TIME!


5/15

How do we measure motion?

DISTANCE is the amount of change in anobjects location (sometimes calleddisplacement)

Example: From mile 3 to mile 20 in the L.A.

Marathon is a distance of 17 miles. Units of Measurement for Distance:

Miles (mi)

Meters (m)

Kilometers (km) Feet (ft)

Inches (in)

Centimeters (cm)


6/15

TIME is how long it takes any object to

travel a certain distance. Often found by subtracting the starting time

from the ending time Example: a plane takes off at 6:00 pm and lands at

9:00 pm, the time of travel would be 3 hours.

Units of Measurement for Time: Hours (hr)

Minutes (min)

Seconds (s)


7/15

RATE or SPEED is how fast an object

travels a certain distance. SPEED is calculated by dividing the

DISTANCE traveled by the TIME it took totravel.

Units of Measurement for Rate or Speed: Miles per hour (mi/hr)

Meters per second (m/s)

Kilometers per hour (km/hr)

Feet per second (ft/s)


8/15

What does motion look like on a graph?

TIME (s)

0 1 2 3 4 5

8

10

6

4

2

D

I

S

T

A

N

C

E

(m)

Distance(m) Time (s) Rate (m/s)

0 0 0

2 1 2

4 2 2

6 3 2

8 4 2

10 5 2

0

The slope in this graph is constant, representing constant (or unchanging) speed. We knowthe object is in motion, because we can see as time increases, the distance traveled alsoincreases.

The slope of the line on a distance vs.time graph represents rate (orspeed).


9/15

How about this?

TIME (s)

0 1 2 3 4 5

8

10

6

4

2

D

I

S

T

A

N

C

E

(m)


0 0 0

4 1 4

8 2 4

8.67 3 0.67

9.33 4 0.67

10 5 0.67

0

The slope in this graph is not constant, meaning speed is changing. During the first 2seconds, the object travels 8 m with a speed of 4 m/s, and for 2-5 seconds, the objecttravels only 2 m with a speed of 0.67 m/s. However, the AVERAGE SPEED (dashedline) for the entire trip is 2 m/s (10 m / 5 s).



10/15

What about this graph?

TIME (s)0 1 2 3 4 5

8

10

6

4

2

D

I

S

TA

N

C

E

(m)


0 0 0

6 1 6

6 2 0

6 3 0

6 4 0

6 5 0

0

The slope in this graph is not constant, meaning speed is changing. During the first second,the object travels 6 m with a speed of 6 m/s, but afterwards (1-5 seconds) the object is notchanging its location and is stopped with a speed of 0 m/s. Here the average speed is 1.2m/s (6 meters / 5 seconds)



11/15

We can solve for any variablewith the D=RT Formula!

DISTANCE = RATE X TIME

DISTANCE = RATE

TIME

DISTANCE = TIMERATE

D = RT

D = RT

D = TR

S l P bl


12/15

Sample Problem At what speed did a plane fly if it

traveled 1760 meters in 8seconds? Solution:

Step 1 Write the Formula andidentify what you know. Step 2 Substitute the numbers

for letters and units of

measurements. Step 3 Solve for the missing

variable.


13/15

The Solution1. d = r x t

d = 1760 m

t = 8 sr = ?

2. 1760 m = r x 8 s

1760 m / 8 s = r3. r = 220 m / s


14/15

Practice Problems

1.

A car travels 240 kilometers in3 hours. What is the speed ofthe car during that time?

2. The speed of a cruise ship is50 km/hr. How far will the shiptravel in 14 hours?

3. A runner has a pace of 5 km/hr.How long will it take him to run10 kilometers?


15/15

The End

Measuring Motion 2013

Documents