motion - katy independent school...
TRANSCRIPT
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.