TwiddleLab / Courses / Physics
Energy: The Universe's Currency
Lessons
- Energy Changes Form (5 min): Energy is a store that things have. Height and motion are two of its forms.
- Height Energy: mgh (7 min): Lifting something stores height energy (gravitational potential energy): E = m × g × h.
- Motion Energy: ½mv² (7 min): Motion energy (kinetic energy) is KE = ½ × m × v²: mass in kg, speed in m/s, energy in joules.
- Conservation: The Skate Park Rule (7 min): In a closed system with no friction the total energy never changes: mgh + ½mv² stays the same.
- Where Energy Goes: Friction and Heat (7 min): Friction and bumps turn useful energy into thermal energy (heat): warm wheels, brakes, a warm ball and floor.
- Work: Force Times Distance (7 min): Work is energy moved by a force: W = F × d, force in newtons times distance in metres. 1 J = 1 N·m.
- Power: How Fast Energy Flows (7 min): Power is how fast energy is moved: P = W ÷ t, energy in joules divided by time in seconds.
- Springs Store Energy (7 min): Hooke's law: a spring pulls back with F = k × x. x is the stretch in metres, k the spring constant in N/m.
- Efficiency: Where Your Energy Goes (7 min): A Sankey diagram draws energy as arrows whose width is the amount. What goes in always equals what comes out.
- Project: Design a Roller Coaster (8 min): A coaster gets all its energy from the lift hill: mgh at the top. After that it only trades height for speed and loses some to heat.
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