# 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.

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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, 5 1 / 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? 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. WARNING: This lesson may alter your weight! The confusion arises because most people use the word ‘weight’ when scientists would use the word ‘mass’.

What are mass and weight? Mass is the amount of matter in an object and is measured in kilograms. 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. Mass and weight are not the same! Mass is not a force and has the same value anywhere in the Universe, including outer space.

Weight and mass on different planets

Why does weight vary? Gravity is the force that attracts objects with mass towards each other. The Earth has a bigger mass than the Moon and so exerts a stronger gravitational pull on the apple. For example, an apple will have the same mass on Earth as on the Moon, but its weight will be different. The bigger the mass of the object, the stronger the force of gravity.

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 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. The units for these quantities are as follows:

Calculating the weight of a car A car has a mass of 10,000 kg. weight = mass x gravitational field strength weight = 10,000 kg x 10 N/kg weight = 100,000 N What is the weight of the car? (Use 10 N/kg as the value of the gravitational field strength.)

Calculating the weight of an astronaut An astronaut and his equipment have a mass of 150 kg. (Use 1.6 N/kg as the value of the gravitational field strength.) What is the weight when he is standing on the Moon? 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.. DD escribe that radio signals take a long time to travel through the Solar System EE xplain that manned spacecraft need to take food, water and oxygen KK now that unmanned spacecraft can withstand conditions that are lethal to humans SS tate that unmanned spacecraft can send back information on: temperature, magnetic field and radiation; gravity, atmosphere and surroundings Higher paper DD escribe what a light-year is and its use in measuring very large distances EE xplain the advantages and disadvantages of using unmanned spacecraft to explore the Solar System

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