National 5. Dynamics and Space

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Susan Dawson
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1 North Berwick High School National 5 Department of Physics Dynamics and Space Section 2 Space Exploration & Cosmology Problem Booklet

2 Newton s Third Law 1. State Newton s Third Law. 2. Identify the Newton pairs in the following situations. 3. What engine thrust must be produced by a rocket of mass 3 x 10 6 kg in order to produce an acceleration of 1 4 ms -2 in space? 4. A water rocket has a mass of 0 8 kg and is launched in a school playground with an initial upwards thrust of 12 N. What is the weight of the water rocket in the playground? What is the initial acceleration of the rocket in the playground? If this water rocket were launched from the moon, what would be its initial acceleration? (Remember to find the new weight first!)

3 5. A rocket is launched from Earth with an initial acceleration of 2 5 ms -2. The mass of the rocket is kg. (d) Calculate the unbalanced force acting on the rocket during its launch. What is the weight of the rocket? Calculate the engine thrust of the rocket. What engine thrust would be required to launch this rocket from the moon with the same acceleration? 6. A space shuttle has a weight of 1 8 x 10 7 N on Earth. Its engines produce a thrust of 2 7 x 10 6 N during part of its journey through space. (You will need to refer to a data sheet for parts of this question.) (d) (e) (f) Calculate the mass of the shuttle. What is the acceleration of the shuttle in space while its engine thrust is 2 7 x 10 6 N? Could the shuttle have been launched from Earth with this engine thrust of 2 7 x10 6 N? Explain your answer. The engine thrust was 2 7 x 10 7 N during the launch from Earth. What was the acceleration of the shuttle during its launch? If a similar shuttle was launched from Venus with an engine thrust of 2 7 x 10 7 N, what would be the acceleration of this shuttle during lift off? What engine thrust would be required in order to launch this shuttle from Jupiter with an acceleration of 5 ms -2? 7. A small piece of metal of mass 2 kg falls from a satellite and re-enters the Earth s atmosphere at a speed of m/s. If all its kinetic energy changes to heat calculate how much heat is produced?

4 8. A shooting star is a meteoroid that enters the Earth s atmosphere and is heated by the force of friction which causes it to glow. A certain meteoroid has a mass of 30 kg and enters the atmosphere at a speed of m/s. Its specific heat capacity is 600 J /kg o C. Calculate the heat energy produced when all the meteoroids kinetic energy is converted to heat. Calculate the rise in temperature of the meteoroid as it re-enters the atmosphere. 9. The nose section of the shuttle is covered with 250 kg of heat resistant tiles which experience a rise in temperature of o C during the shuttle s journey back through the Earth s atmosphere. The shuttle is slowed from m/s to 100 m/s during this part of the journey. shuttle enters Earth s atmosphere United Sta tes v = m/s v = 100 m/s United St ate s How much kinetic energy does the nose of the shuttle lose? How much heat energy is produced at the nose during re-entry? Calculate the specific heat capacity of the material used to make the nose tiles. 10. A multistage rocket jettisons its third stage fuel tank when it is empty. The fuel tank is made of aluminium and has a mass of kg. (specific heat capacity of aluminium is 900 J/kg o C) Calculate the kinetic energy lost by the fuel tank as it slows down from m/s to m/s during its journey through the atmosphere. How much heat energy is produced? Calculate the rise in temperature of the fuel tank.

5 11. In 1962 the communications satellite Telstar was used to relay the first live television pictures from the east coast of the U.S.A to Britain. Telstar orbited the earth at a height varying from 320 km to 480 km. Calculate how long it would take for a 3 cm microwave signal to travel to the satellite if it was 320 km above the transmitter. How much longer would it take for the signal to reach the satellite when it was 480 km above the transmitter? 12. Read the information below and use it to answer the questions that follow. The first effective telecommunications satellite was called Telstar. It was launched in 1962 and orbited the earth in 150 minutes. Telstar was used to transmit a single television link or a limited number of telephone calls for 20 minutes in each orbit. In 1964 an experimental satellite called SYCOM was launched into an orbit km above the earth s surface. SYCOM took 24 hours to complete one orbit of the earth. Nowadays many telecommunications satellites are placed in orbits km above the earth although this is very expensive to do. To communicate with satellites special dish aerials are used which are positioned at satellite ground stations. One such station in Britain is situated at Goonhilly in Cornwall. Goonhilly has a number of microwave dish aerials which transmit and receive information from geostationary satellites placed above the Atlantic and Indian oceans. Dish aerials are used for two reasons: 1. The transmitted signal is formed into a narrow beam by reflection from the dish. This makes it easier to direct the signal to the satellite.

2. The received signal is amplified up to 1 000 000 times by the dish s ability to reflect incoming signals to a central detector.

6 2. The received signal is amplified up to times by the dish s ability to reflect incoming signals to a central detector. The dish aerial shown is situated at Goonhilly and has a diameter of 32 m. It transmits microwave signals of frequency 6 GHz to the satellites and receives microwave signals of frequency 4 GHz relayed from the satellites Which satellite mentioned in the passage was in a geostationary orbit? How long would it take for a 14 GHz signal to travel km to reach SYCOM? Copy and complete the dish diagram to show how it is used to transmit a narrow beam signal to a satellite. aerial (d) Explain, using a suitable diagram, why the dishes used at Goonhilly to receive signals from satellites are large. 13. The star Vega is 27 light years from earth. How far away is Vega in metres? 14. The star Beta Centauri is 300 light years from earth. How long does it take light to travel from this star to the earth? 15. Andromeda (M31) is the nearest galaxy to the Milky Way and can just be seen with the naked eye. Andromeda is 2.1 x m away from the Milky Way. How long does it take for light from Andromeda to reach our galaxy?

7 Solutions x 10 6 N 4. 8 N 5 ms ms x 10 6 N 1.6 x 10 7 N 2 x 10 7 N (d) 6.56 x 10 6 N x 10 6 kg 1.5 ms -2 no; thrust is less than weight (d) 5 ms -2 (e) 6 ms -2 (f) 5.58 x 10 7 N x 10 7 J x 10 8 J C x J 1.25 x J J/kg C x J 4.8 x J C x 10-3 s 5.33 x 10-4 s 12. SYCOM 0.12 s x m years x s ( approx. 2.2 million years)

SECTION 1 - SIGNALS FROM SPACE 2 SECTION 2 - SPACE TRAVEL 5 SPACE PHYSICS REVISION QUESTIONS 19 APPENDIX (I) DATA SHEET 24

Contents Page SECTION 1 - SIGNALS FROM SPACE 2 Distances in Space 2 Ray Diagrams 3 SECTION 2 - SPACE TRAVEL 5 Weight 5 Weight, Thrust and Acceleration 8 Projectiles 12 Re - Entry 16 SPACE PHYSICS REVISION