Gravity and Other Forces

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two objects dropped at the same time

Slide 20

On the Moon – Apollo 15

http://nssdc.gsfc.nasa.gov/planetary/image/featherdrop_sound.mov

A heavy geological hammer and a falcon feather were dropped from the same height.

They hit the lunar surface at the same time.

astronaut David Scott

NASA pictures

Slide 21

Hippo jump

Slide 22

Hippo jump

Force of gravity

Slide 23

Saved?

Slide 24

Hippo is still falling quickly

Slide 25

Hippo is still falling quickly but not getting faster

How do we know?

Force of gravity

air resistance

Slide 26

How can we slow Hippo down?

What can you change?

Slide 27

Launching a satellite

The cannon ball must move very quickly to orbit the earth.

The Moon orbits the Earth

Slide 28

The Moon

The Earth

Slide 29

The Moon

The Earth

Slide 30

On the Moon

NASA pictures

Slide 31

Very heavy boots- Why?

Answers?

No gravity on the Moon

Weightless on the Moon

To stop them floating away

They weigh very much less than on Earth

To stop huge bounces

The Moon’s gravity is very much less than the Earth’s gravity

Slide 32

32

Weightless?

or are they?

(NASA pictures)

Slide 33

33

apparently weightless (pictures or animation only –not a demonstration)

Slide 34

34

GRAVITY

Things fall

Things have weight

Things stay in place

Slide 35