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.

Hands-On Activity: Ramp Race

Supply List

• A smooth ball (marble or small rubber ball)
• A board, folder, or stiff piece of cardboard for a ramp
• Books of different heights to prop the ramp
• A ruler or tape measure
• A notebook and pencil

Instructions

• Set up the ramp at a low angle using one book under one end. Release the ball from the top of the ramp and let it roll across a smooth floor. Measure how far it travels from the bottom of the ramp and record it.
• Raise the ramp to a medium angle using two books. Release the ball from the same position at the top. Measure and record how far it travels.
• Raise the ramp to a high angle using three books. Release the ball and measure again.
• In your notebook, record all three results in a chart: ramp height vs. distance traveled.
• Write a sentence explaining the pattern you see. What happens to the energy of the ball as the ramp gets higher? Where does that energy come from? Where does it go after the ball stops?

Discussion: Ask learners why the ball always slows down and stops even on a smooth floor. Where does the kinetic energy go? (Into heat from friction with the floor.) Challenge them: could we ever build a ramp that makes the ball go farther than the energy we put in? Why not?