Transcript Exploring our Solar System

Exploring our Solar System
P2f part 2
Objectives
In this lesson we should learn:
• about the distances involved in space
travel
• about manned and unmanned space flight
• how very large distances are measured in
space
Outcomes
Foundation Paper
You should now be able to..
• Describe that radio signals take a long time to travel
through the Solar System
• Explain that manned spacecraft need to take food, water
and oxygen
• Know that unmanned spacecraft can withstand
conditions that are lethal to humans
• State that unmanned spacecraft can send back
information on: temperature, magnetic field and
radiation; gravity, atmosphere and surroundings
Higher paper
• Describe what a light-year is and its use in measuring
very large distances
• Explain the advantages and disadvantages of using
unmanned spacecraft to explore the Solar System
Who wants to go into space?
What do you think about space
travel?
• It isn’t cheap
• Are there too many dangers with tonnes of
metal floating around above our heads?
• What should happen to the International
Space Station stuck in budget wrangles?
• What do you think about Virgin Galactic
which announced the construction of a
$200 million spaceport in 2005 to take
tourists into low earth orbit?
The speed of light is the fastest speed that
could EVER be achieved.
The speed of light is 300 000 km per SECOND!!
(That’s 186 000 miles per second)
Light takes 2 seconds to reach the Earth from
the moon
- it takes it 8 minutes to reach the Earth from
the Sun
If you were in a spaceship that travelled at the
speed of light and you started a journey from the
Sun it would take:
about
3 minutes to reach Mercury,
5 minutes to reach Venus,
8 minutes to reach the Earth,
51/2 hours to reach Pluto,
4 years to reach the next star,
5000 years to reach the edge of the galaxy,
50 000 years to reach the next galaxy,
500 000 years to reach the next Cluster!!
Real rockets don’t travel at the speed of light,
they travel MUCH slower.
The Apollo missions took 4 days to reach the
moon - at the speed of light it would have
taken 2 seconds!!
These rockets were travelling roughly 200 000
times slower than light.
At this speed it would take 125 YEARS to get
to Pluto!
How far…
•
•
•
•
Earth is 150 000 000Km away from the sun.
Light travels 300 000km each second
So light takes about 8minutes to reach Earth.
Very large distances in space are measured in
light years- the distance that light travels in 1
year (9 500 000 000 000 000 Km)
• The next star nearest to Earth (after the sun) is
called Proxima Centauri and is 4.22 light years
away.
Calculating how long light takes…
• Light travels at a speed of 300 000 000 m/s.
• How long does light from the Sun take to reach
Earth? (distance of Earth from the Sun is 150
million km)
• Distance from earth to the sun = 150 000 000
000 meters
• 300 000 000
150 000 000 000
= 500 seconds (/60 =8.3 minutes)
Confused about weight and mass?
WARNING: This lesson may alter your weight!
Have you ever heard anyone
saying that “the scales don’t tell
the truth about their weight”?
You may be surprised to hear
that they are right!
Scales give a reading in kilograms,
which are the units of mass, not
the units of weight.
The confusion arises because most
people use the word ‘weight’ when
scientists would use the word ‘mass’.
What are mass and weight?
Mass and weight are not the same!
Mass is the amount of matter in an object and is
measured in kilograms.
Mass is not a force and has the same value anywhere
in the Universe, including outer space.
Weight is a force and is caused by the pull of gravity
acting on a mass. Like other forces, weight is measured
in newtons and has both magnitude and direction.
Weight has different values depending on where the
object is in the Universe.
Weight and mass on different planets
Why does weight vary?
Gravity is the force that
attracts objects with mass
towards each other.
The bigger the mass of the
object, the stronger the
force of gravity.
For example, an apple will
have the same mass on
Earth as on the Moon, but
its weight will be different.
The Earth has a bigger mass
than the Moon and so exerts
a stronger gravitational pull
on the apple.
Weight and mass on the Moon
How do we calculate an objects weight?
The weight of an object depends on its mass and the
gravitational field strength:
weight = mass x gravitational field strength
The units for these quantities are as follows:
 Weight is measured in newtons (N).
 Mass is measured in kilograms (kg).
 Gravitational field strength is measured in
newtons per kilogram (N/kg).
The gravitational field strength depends on the force of gravity.
On Earth it is 10 N/kg, but it varies depending on planet size.
Calculating the weight of a car
A car has a mass of 10,000 kg.
What is the weight of the car?
(Use 10 N/kg as the value of
the gravitational field strength.)
weight = mass x gravitational
field strength
weight = 10,000 kg x 10 N/kg
weight = 100,000 N
Calculating the weight of an astronaut
An astronaut and his equipment
have a mass of 150 kg.
What is the weight when he is
standing on the Moon?
(Use 1.6 N/kg as the value of
the gravitational field strength.)
weight = mass x gravitational
field strength
weight = 150 kg x 1.6 N/kg
weight = 240 N
Calculating weight and mass
Outcomes
Foundation Paper
You should now be able to..
Describe that radio signals take a long time to travel
through the Solar System
Explain that manned spacecraft need to take food, water
and oxygen
Know that unmanned spacecraft can withstand
conditions that are lethal to humans
State that unmanned spacecraft can send back
information on: temperature, magnetic field and
radiation; gravity, atmosphere and surroundings
Higher paper
Describe what a light-year is and its use in measuring
very large distances
Explain the advantages and disadvantages of using
unmanned spacecraft to explore the Solar System
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