15. 299,792 kilometers per second = 1,079,251,200 km/hr !!!
186,287 miles per second = 670, 633,200 mph
• A traveler, moving at the speed of light, would
circumnavigate the equator approximately 7.5
times in one second. By comparison, a traveler
in a jet aircraft, moving at a ground speed of 500
mph, would cross JUST the continental U.S.
once in 4 hours.
• It takes 499.0 seconds (8 min) for light to travel
from the Sun to the Earth
19. Question #8
• Is motion relative?
• Yes or No?
Are we ever really standing still?
20. Yes, All things are in motion.
• You may be perfectly still yet the
earth is spinning on its axis and
orbiting the sun.
• The sun orbits the center of the
galaxy, our galaxy and
Andromeda are moving toward
one another, most of the other
galaxies are moving away.
21. So to measure motion in a meaningful way,
we measure it relative to the observer or
another object we consider not to be moving.
When you pass a car on the highway
moving in the same direction, you
may be going 70mph, and the other
car 65mph. But your speed relative to
the other car is 5mph.
When the shuttle docks with the space
station the two orbiting objects approach one
another at a very slow speed relative to one
another, but both are orbiting at 17,000mph
relative to the surface of the earth.
22.
23. •Motion is a change in position relative to
your surroundings.
•An object moves when it speeds up, slows
down or changes direction.
Main IDEAS
45. A car travels 200 m in
10 seconds. What is
the average speed of
the car?
ANSWER: Ave speed= total d/total time
= 200m/10s
20 m/s
46. Definitions:
A change in position in a certain amount of time is __________.
__________________ is the rate at which an object moves and
is determined by dividing ____________ by _____________.
_________________________ is speed that does not change.
_________________________ is calculated by dividing the
total distance by the total time.
