Mechanical energy is a combination of the energy of motion or position. This type of energy describes objects that are moving or could move. A moving ball can have energy from motion. An arrow can also have the energy of motion. Both are types of mechanical energy. Can you think of some other examples? Where does the energy of motion come from? It comes from the energy created by position. This energy is stored energy. This means it is not moving yet, but it has the potential to move. How can you store energy? The arrow gains energy from the drawn bow. As the arrow is released, the bow releases its stored energy and puts the arrow into motion. Can you think of some other ways to store energy using position? 

How is energy stored in a bow and arrow?


Is this an insect or an animal? A snail is an animal just like you and me. Thats right, you too are an animal. No, you don't look like a snail. You do have some things in common. Animals can be divided into many groups. These groups are decided based on their characteristics. All animals have some basic features in common. That does not mean they are the same. They also have many differences. For example, snails are mollusks and not insects. Mollusks have a unique set of features. Notice the large foot that allows it to move. Yes, it only has one foot. Did you notice the long antennas on its head? This is where the snail's eyes are. They are on the end of the antenna. They are not on its head like most animals. The foot and eyes are unique features. Scientists use these features to place animals into groups. 

What common feature do mollusks and snails have?


You just got done with a long run. You are gasping for air. Why does your body react this way? What is the purpose of breathing? All the cells of your body need oxygen to work properly. Your bodys circulatory system works with the respiratory system to deliver the oxygen. Your blood carries red blood cells. The main job of red blood cells is to carry oxygen throughout your body. The red blood cells get oxygen in the lungs. The lungs are the main organs of the respiratory system. The respiratory system is the body system that takes in oxygen. It then releases carbon dioxide back to the atmosphere. The carbon dioxide is the waste material from the cells. 


What cells carry oxygen to the lungs?