2. (a) A light year is the speed of light in m/s multiplied by the number of seconds in one year.

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2 Self Check 1 Answers 1. Copy and complete the table below: Object Moon Sun Planet Star Solar System Galaxy Universe Definition A natural satellite of a planet Star undergoing nuclear fusion A large body in orbit around a star A large body of matter undergoing nuclear fusion. Group of planets orbiting a central star A large cluster of many hundreds of thousand of stars. All of Space 2. A light year is the speed of light in m/s multiplied by the number of seconds in one year. Distances in space are so large that light years must be used. 3. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. 4. B 5. D

3 Self Check 2 Answers 1. The Earth casts a shadow on the moon. Depending on the position of the Sun, the shadow will be different each night. 2. (c) C B A A. SUN Moon e Earth B. Moon C. SUN e SUN e Moon Earth Earth 3. During a solar eclipse the moon passes between the Earth and the Sun. 4. During a solar eclipse it is the moon that passes between the Earth and the Sun. During a lunar eclipse it is the Earth which passes between the moon and the Sun.

4 Self Check 3 Answers 1. Use the information in the passage below to copy and complete the diagram A telescope has two lenses enclosed in a light-tight tube which also enables the telescope to be focused. The lens with the long focal length is called the objective lens and the lens with the short focal length, the eyepiece lens. Objective Lens Light-tight Tube Eyepiece Lens 2. Increasing the size of the objective lens will make the image brighter. 3. When using an optical telescope only light signals are detected. Therefore all other members of the electromagnetic spectrum are not detected (gamma rays, x-rays, ultraviolet, infrared, microwaves, radio waves). 4. Radio telescopes can pick up signals that the human eye cannot. 5. The Hubble Space Telescope orbits outside of the Earth s atmosphere. This means that the images are not distorted by the gases in our atmosphere.

5 Self Check 4 Answers 1. Identify the following Newton Pairs: (c) (d) Thumb pushes down on pin, pin pushes up on thumb. Foot kicks ball, ball exerts a force back onto the foot. Rocket pushes down on exhaust gases, exhaust gases pushes up on rocket. Balloon pushes back on gases, gases push the balloon forward. 2. It is not the ground that pushes the rocket upwards. It is the exhaust gases.

6 Self Check 5 Answers 1. Mass is the amount of matter in an object and is measured in kilograms (kg). Weight is a force due to gravity and is measured in Netwons (N). 2. Weight (N) Mass (kg) Gravitational field Strength (N/kg) The gravitational field strength on the moon is less than that on Earth. The objects mass will be the same on the moon as it was on Earth. The object will weigh less on the moon.

7 Self Check 5 Answers Continued 4. Weightlessness (c) The Earth s gravitational pull holds a satellite in orbit. The appear to be weightless, so they need a seatbelt to ensure they stay on the bed. 5. The shuttles need solar panels to get change light energy from the Sun into electrical energy. The Shuttles are designed with heat resistant tiles on their bottom surface. The shuttle enters the atmosphere at a particular angle, this slows the shuttle down ,250 years Space travel using Voyager-1 s method is not possible as the time required to travel distances is far too long.

8 Self Check 6 Answers 1. Read the following extract and answer the questions which follow: The Earth is 4.5 billion years old (approximately!) and humans have only existed for a very small percentage of that time due to the time it takes to evolve. With a huge number of planets discovered outside our solar system there is much discussion of extra-terrestrial life. Planetary Conditions for Extraterrestrial Life? What conditions would be required on another planet to allow life to be created? (Consider the Earth s position in the solar system, the conditions on Earth when life developed.) There is no right or wrong answer, but your answer must have solid logical ground. Evidence for UFO and Extraterrestrials On Earth there are some people who claim to have seen strange objects flying through the sky at great speeds with bright lights. These so called Unidentified Flying Objects (UFOs) are often later found to be objects such as weather balloons or new fighter jet aircraft being developed by the military. Some people also claim to have been abducted and used in experiments conducted by aliens. Other people claim to have seen little green men. Sometimes there are alternative explanations. Sometimes people are seeking attention and find ways to alter photographs to fake something that appears difficult to explain. Even so, there are some cases that nobody can give a logical explanation for and there is no evidence of fabrication (faking evidence). (c) (d) (e) UFO stands for Unidentified Flying Object. UFO sightings often turn out to be weather balloons or new fighter jet aircrafts. Some people do this to seek attention. No, some cases remain unexplained. No, even although the majority of sightings are hoaxes, there are still some sightings unexplained.

9 Self Check 7 Answers 1. Stars are made from a mixture of different gases. Stars are so hot as they are undergoing nuclear fusion. 2. As a star ages it uses up it s fuel for nuclear fusion. 3. A star around the size of our Sun will become a Red Giant. Once the outer gases have cooled and expanded there is a white dwarf star left. This will eventually become a black dwarf star. 4. When a massive star dies a black hole may be formed. 5. Cosmologists have several theories on how the Universe will end. The Big Freeze describes the prediction that the Universe will continue to expand. As the Universe expands the stars will begin to die, once all of the stars have died the Universe will drop in temperature. If the Universe does have a large enough mass, then it will stop expanding and it will begin to collapse. This is called The Big Crunch and describes a Big Bang Reversal (c) (i) Cosmologists have recently discovered that the Universe is accelerating as it expands. (ii) This discovery could suggest the Universe will end with The Great Rip

10 Extra Work Self Check 1 Answers 1. The table below gives information about planets that orbit the Sun. The distance from the Sun is measured in Gigametres, Gm. (1Gm = m) Planet Distance from the Sun (Gm) Period (days) Mass (Earth Masses) Earth Jupiter Mars Saturn Venus (c) Mercury. Anything in the range between Mars and Saturn days are in one Saturn year. 2. Scientists often use graphs to estimate a particular value. Show your graph to your teacher Gm

11 Extra Work Self Check 2 Answers 1. An objective lens with a larger diameter will provide a brighter image. Radio telescope and reflecting telescope are two other types of telescope. 2. The Hubble space telescope orbits the Earth and takes photographs of planets and Galaxies far away. Images from Hubble are much clearer as the images are not distorted by the atmosphere. The Earth s force of gravity pulls the Hubble Space Telescope towards the ground. However, as the Earth is curved, the telescope does not hit the ground.

12 Extra Work Self Check 3 Answers 1. Newton s Third Law of Motion states that every action has an equal but opposite reaction. The rocket s mass will decrease as it is using up fuel. 2. 0N The diver and scales are falling towards the Earth at the same rate. The diver is in freefall and appears to be weightless.

13 Extra Work Self Check 4 Answers 1. (i) At 200 km, g = 3.6 N/kg (ii) 2120 N 2. Mars is the closest planet to Earth in terms of distance. There are also signs that water was once on the surface of Mars. Mars is much further away than the moon.

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