Building directly on Lesson 25, learners discover how force and energy are connected, but not the same thing. The lesson establishes force as the go-between that moves energy from one object to another, introduces simple machines as tools that change how force is applied without creating new energy, and explores gravity as a usable energy source. The lesson closes with the conservation of energy: energy can be moved and transformed, but never created or destroyed.

Key Ideas

• Force is the go-between: when energy moves from one object to another, force is almost always what makes the transfer happen.
• Simple machines change how force is applied, they can reduce the force needed or change its direction, but they do not create energy.
• A lever uses a pivot point to multiply force. A ramp (inclined plane) spreads a large force over a longer distance, making lifting easier.
• Gravity can be harnessed as a usable energy source. Waterwheels and hydroelectric dams both capture the energy of falling water.
• Energy cannot be created or destroyed, only transferred or transformed. This is why a perpetual motion machine is impossible.
• When a moving object slows down from friction, its kinetic energy does not disappear, it converts to heat.

Vocabulary

• Simple Machine: A tool that changes the direction or size of a force. Examples include levers, ramps (inclined planes), and pulleys.
• Lever: A rigid bar on a pivot point that can multiply force or change its direction.
• Inclined Plane: A slanted surface (ramp) that makes it easier to raise an object by spreading the work over a longer distance.
• Friction: A force that resists motion between two surfaces in contact. Friction converts kinetic energy into heat.
• Conservation of Energy: The principle that energy cannot be created or destroyed, only transferred or transformed.

Discussion

• How do simple machines make a job easier without creating extra energy? What are they actually changing?
• Why does a ramp make it easier to move something heavy upward? What do you give up in exchange for using less force?
• How can a lever help you move something that is much heavier than you are? Where does the extra force come from?
• A ball rolling across the floor eventually stops because of friction. Where did its kinetic energy go?
• How can a hydroelectric dam use gravity to produce useful energy? Where did the water's energy come from in the first place?

Phet Simulation Recommendation: https://phet.colorado.edu/en/simulations/forces-and-motion-basics