Across
- 3. a device that increases or decreases the voltage of an electrical current.
- 5. two__________________-something flat that exists in 2 directions; height and width.
- 7. waves ultrasound are ___________ ___________that are smaller, or of a higher frequency, than can be heard by human beings.
- 10. searched for food.
- 11. Rockets were first developed over 2000 years ago in ___________________________.
- 13. ________________________________ can be measured in amps and volts.
- 16. a method of using sound waves to locate and identify objects.
- 19. An Internal Combustion Engine is an engine that is powered by the energy of___________________.
Down
- 1. gas that leaves an engine.
- 2. a medical or scientific tool used for investigating.
- 4. people without a permanent home who travel from place to place.
- 6. an ancient culture located in the area that is Iraq today.
- 8. a short tube that becomes narrower on one end.
- 9. the last part of the stone age.
- 12. may be the most important process that human beings ever developed.
- 14. safe to eat.
- 15. Compared to x-rays, which use a form of _______________________________ultrasound is much safer.
- 17. _________dimensional-something solid that exists in three directions; height, width, and depth.
- 18. military rockets that carry explosives to their targets.