Windmill Forces

In this lesson, students build model windmills to observe the transfer of energy and then carry out an experiment to test how windmill blades in balanced and unbalanced positions affect the amount of marbles a windmill can lift.

• Matter and energy are constantly interacting because matter can only change when enough energy is present.
• Energy can be stored or in motion.
• Windmills are structures that capture the wind’s kinetic energy to do work.
• Windmills apply the scientific concept that energy can be transferred into or out of objects or substances.
• Windmills need to be balanced in order to work. They also need to reduce friction.
  
  

• How is energy different from matter? How are matter and energy connected?
• What do all forms of potential energy have in common?
• How does the strength of the wind affect how much work a windmill can do?
• What are the parts of a windmill and how do the parts connect together? Why do windmill blades need to be angled?
• Why is it important for a windmill to be balanced? What would happen if a windmill’s blades were unbalanced?
• How does friction affect a windmill’s motion?
  
  

Misconception: If an object is at rest, there are no forces acting on it.

Fact: There are forces everywhere. When an object is at rest, all of the forces acting on it are balanced.

Misconception: A force is necessary to keep an object moving.

Fact: An unbalanced force changes an object’s motion. An object that is already in motion will continue moving until acted on by an unbalanced force, such as friction.

Misconception: Only moving objects have energy.

Fact: Nonmoving objects have stored potential energy.

Balanced : when all of the forces acting on an object are equal

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

Kinetic Energy: energy of motion

Potential Energy : energy that is stored

Unbalanced : when the forces acting on an object are not equal

Wind : moving air molecules

Windmill : a structure that captures the wind’s kinetic energy to do work

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

Windmills in Holland

The Netherlands is a country. It is located in northern Europe. It is famous for its many windmills across the country.

Windmills have an important job in the Netherlands. They helped people remove water from land. This was necessary because its land is not much higher than the sea. The name the Netherlands means “Lower Countries.” Much of the land is below sea level.

Windmills pumped water out of the lowlands and back into the rivers. This allowed people to farm the land that used to be covered by water.

Matter and Energy Interact

Windmills pump water because they capture the energy in wind. Wind has energy because it is moving air molecules. When air gets cooler, it begins to sink downward. When air warms up, it rises. This motion creates wind.

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 always interacting. Matter can only change when enough energy is present.

There are different forms of energy. Energy can change from one form to another.

Potential energy is energy that is stored. For example, all matter has a form of potential energy called chemical energy. This energy is stored in atoms and molecules. We eat food because food has chemical energy. Our bodies need that chemical energy to survive.

Kinetic energy is the energy of motion. The more kinetic energy something has, the more work it can do. When the wind blows, it has kinetic energy.

Balancing Forces

Windmills pump water in the Netherlands because they capture the wind’s kinetic energy to do work. This is possible because wind produces a force when it hits the windmill’s blades. Remember that a force is a push or pull that acts on an object, changing its speed, direction, or shape.

Without force, nothing can move. When all of the forces acting on an object are balanced, the object will not change its motion. Balanced means that all of the forces acting on an object are equal. Unbalanced means that the forces acting on an object are not equal.

If you want to change an object’s movement, there has to be an unbalanced force acting on it. An unbalanced force can change the speed or direction of the object. Wind provides the unbalanced force that moves the windmill’s blades.

For the hands-on activity in this lesson, students design windmills and develop a question to investigate how balanced versus unbalanced forces affect how many marbles the windmill can lift. Students compare the maximum number of marbles the windmill can lift with different numbers of windmill blades in balanced and then unbalanced positions. Students use their data from the experiment to explain how the motion of an object is affected by balanced versus unbalanced forces. Students present their conclusions and compare results with other student teams, evaluating reasons for possible differences.