A substance that cannot be broken down into even by chemical means is called an element. About 90 elements on the Periodic Table can be found naturally on Earth. Three of the most common ones are aluminium, silicon and oxygen.
Sorry I couldn't give you a more specific answer as your question wasn't multiple choice.
Answer:
An element is a pure substance and is made of only one type of atom; it cannot be broken down into a simpler substance. Overview: In this activity, students practice using the periodic table to look up chemical symbols of elements and use paper circles to construct and compare models of elements and compounds.
Explanation:
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Answer for number 1. Weight is the force of gravity. It acts in a downward direction—toward the center of the Earth.
Lift is the force that acts at a right angle to the direction of motion through the air. Lift is created by differences...
Thrust is the force that propels a flying machine in the direction of motion. Engines produce thrust.
2. For an airplane to takeoff, thrust must be greater than drag and lift must be greater than weight. To maintain level flight, lift must equal weight and thrust must equal drag. For landing, thrust must be less than drag, and lift must be less than weight.
3.When the forward forces are bigger than the opposing forces, you speed up (accelerate). As you go faster, the force of air resistance pushing back on you increases. Eventually, the forces become balanced (the forward forces are the same size as the opposing forces). Once the forces become balanced, your speed stays the same.
4.Every object on Earth has weight, a product of both gravity and mass. A Boeing 747-8 passenger airliner, for instance, has a maximum takeoff weight of 487.5 tons (442 metric tons), the force with which the weighty plane is drawn toward the Earth.
