9 J Gravity and Space

GRAVITY AND
SPACE
In This Topic We Will Learn About:
Gravity and gravitational strength.
Natural and artificial satellites.
The history of the solar system.
Copernicus and Kepler.
Discoveries.
Telescopes and radio telescopes.…read more

GRAVITY AND SPACE
Gravity is a force that always attracts objects.
· All objects produce a gravitational force but only very
large objects make a force big enough to affect us.
· The greater the mass of the object, the greater the strength
of its gravity.
· The further apart two objects are, the lower the force of
gravity between them.…read more

GRAVITY AND SPACE
The Earth's gravity attracts every object on or near the
Earth.
It tries to pull them towards the centre of the Earth.
The Earth pulls every kilogram with a
force of 10 Newtons.
Another way of saying this is to say the
Earth's gravity has a strength of 10 N/kg
or that 1 kg weighs 10 N.
How much would a girl with a mass of 40kg weigh on Earth?
40 x 10 = 400 N…read more

GRAVITY AND SPACE
Different planets, stars and moons have different gravitational
strengths.
· The moon has a gravitational strength of about 1.5 N/kg.
· This means that every kilogram weighs only 1.5 N on the Moon.
How much would a girl with a mass of 40 kg weigh on the Moon?
40 x 1.5 = 60 N
· Jupiter has a gravitational strength of about 20 N/kg.
How much would the same girl weigh on Jupiter?
40 x 20 = 800 N…read more

GRAVITY AND SPACE
Gravity is responsible for keeping our solar system
together.
· All the planets are attracted by the Sun's gravitational pull.
· This keeps them moving around the Sun in orbits and stops them
moving off into outer space.…read more

GRAVITY AND SPACE
Many planets have moons orbiting them.
· Our Moon orbits the Earth because it is attracted by the Earth's
gravitational pull. Jupiter has
more than
20 moons
· Larger planets usually have more moons than smaller planets.
Why is this?
· Because the pull of gravity of a large planet is stronger than
the pull of gravity of a small planet. It is the planet's gravity
that keeps its moons in orbit.…read more