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Across 2. Hydrogen nuclei joining together is known as nuclear ______ 5. 20hZ - 20,000Hz is the range of sound heard by what? 6. You need to suspend the object from a pin, then hang a __________ to get a straight line and mark several points on the object to find the centre of mass 10. Gravity and Centripetal force keeps all planets in this 12. In reflection, this is the ray that goes towards the mirror 13. Part of the national grid which can be step up, or step down 14. Earth's natural satellite 16. A balanced object can be said to be in _______ 18. The point where the mass in an object is concentrated is called the '_____ of mass' 20. Concave mirrors produce a real image in _____ of the mirror 21. The turning effect of a force 23. This type of satellite is put into a high orbit so it moves at the same speed as the Earth turns 26. Light waves are not longitudinal, they are _______ 27. Concave lenses may also be known as this 28. Our galaxy 29. This type of wave is longitudinal

Down 1. A mirror or lens that curves outwards 3. A mirror or lens that curves inwards 4. Sound wave frequencies beyond 20,000Hz 7. Convex lenses may also be known as this 8. This type of satellite is put into a low polar orbit 9. The effect produced when we place a wire carrying an electric current into a magnetic field 11. Calculating image height dividided by object height gives __________ 15. The force acting on an object when it is moving in a circle 17. A star with a large mass will collapse and explode into this 19. When waves change speed and direction when moving between two mediums is it called __________ 20. The higher this is, the more high pitched the sound 22. The force acting on all objects to attract them to one another 23. A group of stars is known as this 24. In reflection, the line that is perpendicular to the mirror at the point where the light rays hit 25. Convex mirrors produce a virtual image _____ the mirror