MOTION

When an object changes position in relation to a reference point over a

period of time, the object is

in motion.

Motion is Relative

You must watch the object that is

moving in relation to another

object that appears to stay in

place.

REFERENCE POINT

A fixed place on Earth’s surface from which

direction and location can be described is

a reference point.

When an object is in motion, you can

describe the direction of its motion using a

reference direction.

Ex. North, South, Up, Down

Determine if an object is in motion

Take Off!

After 30 Minutes

SPEED

The rate at which an object moves is

speed.

Speed depends on two things:

the distance traveled

the time taken to travel that distance

How do you calculate speed?

Calculating Speed

Speed is distance divided by time.

Speed = Distance ÷ Time

Calculate this Speed:

A football field is about 100

m long. If it takes a person

20 seconds to run its length,

how fast was the football

player running?

Calculate this Speed:

Speed =

Speed =

Time

Distance

sec20

100m= 5 m/sec

Remember

to include

the UNITS!!

Speed Brain Food

The list below shows a comparison of

some interesting speeds:

• Cockroach 1.25 m/s

• Kangaroo 15 m/s

• Cheetah 27 m/s

• Sound 340 m/s

• Space Shuttle 10,000 m/s

• Radiant Light 300,000,000 m/s

Constant Speed Is

Speed that does

not change

Are you always traveling at a

constant speed?

Average Speed

Most of the time, objects do not travel at a

constant speed. For example, you

probably do not walk at a constant speed

from one class to the next. Calculating

average speed using a formula is very

useful.

Average Speed Formula:

Average Speed = Time Total

Distance Total

Average Total Total

Speed = Distance ÷ Time

Find the Average Speed:

A bird flies a distance of

100 m, 150 m, and 200 m in

a total time of 50 seconds.

What is the bird’s average

speed?

Find the Average Speed:

Total Distance = 100m + 150m + 200m

= 450 m

Avg. Speed =

Avg. Speed =

Avg. Speed = 9 m/sec

Time Total

Distance Total

sec50

450mRemember

to include

the UNITS!!

Velocity

Velocity is the speed of an

object in a particular direction.

Be careful! Speed & Velocity are not the same thing!

Distinguish Between Speed and Velocity

Speed describes distance and time

Velocity describes distance, time,

and direction.

Velocity or Speed?

An airplane travels

600 km/h.Is this describing the airplane’s speed or

velocity?

Speed

because there is no direction!

Velocity or Speed?

A car travels

75 km/h west on I-10.

Is this describing the car’s speed or

velocity?

Velocity because there is a

direction!

Motion Riddle:

Two birds leave the same tree at

the same time. They both fly at

10 km/h for 1 hour, 15 km/h for 30

minutes, and 5 km/h for 1 hour.

But they don’t end up at the same

place. Why not?

Riddle Answer

The birds went in different

directions!

The birds had the same

speed but had different

velocities.