Kinetic energy · 4:06
Sketchnote in the works
status paste pack ready — Mr. U draws this one next
Unit 08 · Energy arc · 7th grade
Energy
keeps score.
Nothing is gained, nothing is lost — only transferred. Stored as height, spent as speed, taxed as heat. One roller coaster keeps the ledger, and its first rule is the First Hill Rule.
the first hill rule — tallest always comes first
Watch · Khan Academy
The two currencies, explained
Cards · Spaced repetition
Say it like a scientist
Fifteen words. Flip, type, or match — the deck schedules what you're about to forget, and myth cards keep you honest. (It lives in your browser, no account.)
Sketch · sketchnotes
Draw it to know it
One page per video: print the workbook, fill it in while you watch, then check yourself against the key. Mr. U is drawing these next — the band is ready when they land.
Potential energy · 3:44
Sketchnote in the works
status paste pack ready — Mr. U draws this one next
Read · Eleo explains
The beetle's commentary track
Companion articles for the videos — same energy, beetle's mouth. Audio versions land as they're recorded.
Investigate · Performance expectations
Your prediction vs. the real world
Commit first, then let the data reply — a coaster is a natural energy lab. Investigation pages are being designed with Mr. U and land here when they're honest.
Investigations in the works
The coaster already keeps the ledger — the investigation will make you keep it first.
in the worksPractice · Math skills
The energy ledger
Every joule somewhere: the v² discovery, shelf-height PE, coaster bookkeeping, and the First Hill Rule as a word problem. Print the sheet, show your work, check the key.
Myth-busters · tap to flip
Unlearn these three things
Exit ticket · 5 questions
Before you leave the park
No grade, no stakes — just proof the ledger balances. Answer all five to earn the stamp.
question 1 of 5
The phenomenon · the First Hill Rule
No engine. No problem.
Look at any roller coaster: the tallest hill is always the first one, and the cars carry no engine at all. The chain lift drags them up once — and gravity does the rest. What did the lift hill really give them?
01
The lift is a loan
The chain spends energy to raise the cars — and every joule gets stored as height. Potential energy. The whole rest of the ride is the cars spending that loan.
02
The drop is the payday
Over the first drop, stored height becomes speed — potential becomes kinetic. The steeper and taller the drop, the more PE is left to convert.
03
Friction takes a tax
Wheels hum, rails warm, air pushes back — a little energy leaves as heat every meter. That's why every later hill must be shorter: the budget only shrinks.
So — where does the energy go when the ride stops?
The brakes. Friction between brake fins and the car turns the last of the motion into thermal energy — the track literally warms up. The energy isn't gone. It's just done riding.
Manipulative 01 · energy of motion
Kinetic: speed counts squared
KE = ½ × mass × speed². Mass plays it straight — double the mass, double the energy. Speed squares it — double the speed, quadruple the energy. Set the sliders and watch the square bite.
750 J
½ × 60 kg × (5 m/s)²
For scale
The beetle, full scurry — about 0.000009 J. Physics respects him anyway.
You, walking — ~75 J. A nightlight's worth of motion.
You, sprinting — ~1,600 J. Speed squared did that, not effort.
A car at highway speed — ~500,000 J. This is why speed limits are really energy limits.
Manipulative 02 · energy of arrangement
Potential: stored, waiting
Potential energy is energy stored by position or arrangement — height, stretch, or chemical bonds. Gravitational PE = m × g × h: mass × gravity × height. Put the beetle on a shelf.
shelf 3 · 2.0 m
shelf 2 · 1.2 m
shelf 1 · 0.5 m
PE = 0.0005 kg × 9.8 × 0.5 m = 0.0025 J — tiny beetle, tiny budget.
Three storage bins
Gravitational — stored by height. The coaster car at the top, the water behind the dam, the beetle on shelf 3.
Elastic — stored by stretch or squeeze. Rubber bands, springs, a drawn bow.
Chemical — stored in molecular bonds. Food, fuel, batteries. Dinner is a battery that tastes good.
Manipulative 03 · the lab
The Coaster
Release the cart from any height and watch the ledger: potential becomes kinetic, kinetic becomes potential, and friction quietly opens a heat account. Perfect track or real track — your call.
release from
the track
pick a drop. watch the bars keep score.
Standards: MS-PS3-1 — kinetic energy relates to mass and to speed (squared) · MS-PS3-2 — potential energy is stored in a system by the arrangement of its parts · MS-PS3-5 — when kinetic energy changes, energy is transferred to or from the object (NGSS Lead States, 2013). DCIs: PS3.A Definitions of Energy, PS3.C Relationship Between Energy and Forces. CCCs: Scale, Proportion, and Quantity, Systems and System Models, Energy and Matter.