Science · Grade 4 Science
Chapter 1: Energy and Motion
It does not vanish. It goes somewhere.
Watch first. The explanation comes later.
A rolling cart hits a still block. A moment later the cart has stopped and the block is sliding.
Where did the cart’s energy go?
Run it slowly and watch the moment the cart reaches the block.
Step 1 — Predict
The cart stops and the block moves. What happened to the cart’s energy?
Choose what you think will happen. You cannot see the experiment until you do — guessing first is what makes it worth watching.
Now the explanation, after you have seen it happen.
Energy can pass from one object to another, and that passing is called a transfer. Nothing new is made and nothing destroyed. What one object loses, the others gain, which is why you can follow it about like an object of its own.
Transfer Energy moving from one thing to another.
The cart slows down by exactly as much as the block speeds up.
When something stops, its energy did not vanish — it went somewhere. Some went into whatever it pushed. The rest went into rubbing against the surface and the air, which warms them very slightly. Track it down and it is always accounted for.
energy What makes things move, heat up, or light up.
On a smooth surface less energy is lost to rubbing, so the object keeps going longer.
When a rolling ball stops, its energy of motion did not disappear. It went into warming the surface and the air, and into sound. Energy moves between places and forms; it is never destroyed.
By something moving and hitting something else, by heat flowing, by light traveling, and by electric current in a wire. Almost every everyday transfer is one of those four.
Lots of people think
“When something stops moving, its energy is used up and gone.”
The same idea somewhere new.
The block eventually stops too. Its energy goes into rubbing against the ground — which warms both surfaces very slightly. Energy never runs out; it just ends up spread thinly as heat, where it is no longer useful for pushing anything.
Practice makes it stick.
The Marble
Problem 1 of 1
A rolling marble hits a still marble and stops dead. The second one rolls away. What happened?
1 of 4
What is a transfer?
2 of 4
A ball rolls to a stop on carpet. Where did its energy go?
3 of 4
Which picture shows a ball that will travel furthest?
4 of 4
Can energy be destroyed?
Show what you know.
Question 1 of 1
A cart stops and a block starts moving. What is the best description?
Claim, evidence, then reasoning.
The question
The cart stops and the block slides away. Using your fast run and your slow run, write an argument answering the question: did the cart’s energy disappear, or did it go into the block?
Evidence you can use
Fill in all three boxes. The reasoning box is the one that matters most.