Movements of the Earth: Gravity, Inertia, Rotation, Revolution

GravityGravity 1. Pulling force that attracts

objects2. Pulls things down on Earth

GravityGravity

3. Every object has gravity4. Strength depends on mass & distance between objects

GravityGravity

A space station is to be located between the Earth and the Moon at the place where the Earth’s gravitational pull is equal to the Moon’s gravitational pull. Which of these locations would be best? Explain

GravityWhat does gravity do?

1. Holds planets in paths around sun

GravityWhat does gravity do?

2. Keeps moon in its orbit around the Earth

GravityWhat does gravity do?

3. Keeps entire universe moving in an orderly way

InertiaInertia 1. Every object in universe is

moving

InertiaInertia 2. A body in motion stays in

motion3. A body at rest stays at rest4. Unless acted on by a force

InertiaInertia 5. Every object tries to stay

the way it isEither moving or resting

InertiaWhat does inertia cause in space?

1. Moon to keep moving around Earth2. Planets to keep orbiting the sun

InertiaWhat does inertia cause in space?

3. Galaxies to keep moving through space

EARTHParts of the Earth

1. Equator- horizontal line dividing north and south hemispheres

EARTHParts of the Earth

2. Latitude- horizontal lines3. Longitude- vertical lines

EARTHParts of the Earth

4. Hemispheres- N & S, E & W

EARTHParts of the Earth

5. Earth’s axis is tilted 23.5 degrees

EARTH’S MOVEMENTSEarth’s movements

1. Rotation- spins like a top2. Revolution- moves around sun (30km/sec) in oval path

EARTH’S MOVEMENTSROTATION 1. Earth spins on its axis

2. 24 hours= one rotation3. Causes night and day4. Side of Earth facing sun has day

EARTH’S MOVEMENTSREVOLUTION

1. Earth goes around sun (orbits)2. Takes 1 year = 365 1/4 days3. Causes seasons4. Hemisphere tilted toward sun has summer

EARTH’S REVOLUTIONSEASONS 2. When north hemisphere

is tilted toward sun = summer

More direct, intense light rays, warm Earth more

EARTH’S REVOLUTIONSEASONS 3. When north hemisphere

is tilted away sun = winterWeaker, spread out light rays, warm Earth less

EARTH’S REVOLUTIONSEASONS 4. When n. hemi has winter,

s. hemi has summer

EARTH’S REVOLUTIONSEASONS 5. Spring and Fall occur

when neither hemisphere is tilted toward or away from the sun

Equinoxes

Diagram of Earth’s Seasons