Energy and Collisions

In this lesson, students apply their knowledge of matter, mass, and gravity to evaluate how energy and matter interact. They compare the different forms of energy and describe how energy is conserved. They then analyze how all moving objects have energy, which is transferred when objects collide. 

• Energy is the ability to do work (any change in position, speed, or state of matter due to force). Energy is not matter, but it is related to matter because matter can only change when enough energy is present.  
• There are different forms of energy, but all energy is always either being stored or doing work. Energy that is being stored is called potential energy, and energy of motion is called kinetic energy.
• Energy can change from one form to another in an energy system. A system is a set of connected, interacting parts that form a more complex whole.
• Energy is never created or destroyed, but it can be transferred into or out of objects or systems. 
• Moving objects have energy, and the faster an object is moving, the more energy it has. Speed is the rate at which an object covers distance in a period of time.

• What is energy? How is energy different from matter?
• How does energy interact with matter?
• Why is chemical energy a form of potential energy?
• Why is gravitational energy a form of potential energy?
• How is kinetic energy different from potential energy?
• How do objects transfer energy? 
• Why do collisions between two objects often result in a loud sound?
• Why do moving objects eventually slow down? 
• Does a ball have more kinetic energy when it is moving at a fast speed or a slow speed? 

Misconception: Weight and mass are the same thing.

Fact: Weight and mass are two different measurements. Mass measures the amount of matter in a substance, while weight is a gravitational force exerted on an object by a planet or moon.

Misconception: If something isn’t moving, there are no forces acting on it.

Fact: Forces act on objects all the time. When all of the forces acting on an object are balanced, the object will not change its motion.

Atom:  the smallest piece of matter that has the properties of an element; a combination of three subatomic particles: protons, neutrons, and electrons

Cause and effect : a relationship between events or things, where one is the result of the other

Energy: the ability to do work (move an object, heat up an object, charge an object, etc.)

Force : a push or pull that acts on an object, changing its speed, direction, or shape

Friction:  a force that slows motion whenever two objects rub against each other

Gravity: a force of attraction between all matter

Speed: the rate at which an object covers distance in a period of time; measured in meters per second (m/s)

System: a set of connected, interacting parts that form a more complex whole

Work: any change in position, speed, or state of matter due to force

Moving Space Debris

One particular challenge to the International Space Station is space debris. More than 500,000 pieces of space debris orbit Earth. The most common space debris orbiting Earth comes from human-made sources, including old spacecraft that are no longer in use.

Space debris poses a challenge to the International Space Station because in space, objects move with a large amount of speed. Speed is the rate at which an object covers distance in a period of time. It is measured in meters per second (m/s).

Most debris travels at speeds of up to 28,164 kilometers (17,500 miles) per hour. At those speeds, even tiny paint flecks can damage structures. This is because moving objects have energy. The faster an object is moving, the more energy it has.

Energy Changes Matter

Energy is the ability to do work. Work is any change in position, speed, or state of matter due to force. Unlike matter, energy is not made up of atoms. However, matter and energy are constantly interacting. Matter can only change when enough energy is present.

Energy is always either being stored or doing work. Energy that is being stored is called potential energy.

There are different forms of energy. For example, all matter has a form of potential energy called chemical energy. This energy is stored in the bonds that hold together atoms and molecules. The reason we eat food is because food contains chemical energy. Our bodies need that chemical energy to survive.

Energy of motion is called kinetic energy. The more kinetic energy something has, the more work it can do. For example, all moving objects have kinetic energy.

Energy can change from one form to another in an energy system. A system is a set of connected, interacting parts that form a more complex whole.

You are an energy system. When you eat food, you absorb that food’s chemical energy. Your body changes some of that chemical energy into kinetic energy when you run, ride a bike, or turn a page of a book. Your body also stores some of the chemical energy so it can be used later.

Transferring Energy

Energy can also be transferred from one object or system to another. When energy is transferred, it moves into or out of an object or system.

Whenever two objects come into contact with one another, they exert a force on each other for a short period of time. This is called a collision. The reason that even tiny paint flecks can damage the International Space Station is that when two objects collide, the force of that collision causes energy to transfer from one object to another.

When a moving object hits another object, the force of the collision transfers energy into the second object. Some energy is also changed into other forms of energy, such as sound. This is why collisions often make loud noises. The force can also transfer energy that changes the objecs’ motion.

In this lesson, students collect and analyze data on the distance a target cup moves after a collision with marbles moving at different speeds, looking for patterns that might indicate a relationship between an object’s speed and the amount of energy it transfers. Students use the data from the experiment to support or reject their hypothesis about how the speed of an object is related to the amount of energy it transfers during a collision.