Unit 1 · Qualitative Introduction to Energy

Study for the energy exam by doing, not just reading.

Four stations, same skills as the test: name the ideas, build a system schema, size up an energy pie, and take a scored quiz. Everything checks itself — work through it once, then again the night before.

Name Period

Vocabulary & Key Ideas

Type your answer, then hit Check. Short-answer items get a model answer to compare against instead of a grade.

1.Energy is …

2.A change is something you can …

3.Energy is stored in a system in only two ways. Name both.

4.In your own words — what's the difference between a system and its surroundings?

Model answerThe system is the object(s) you choose to focus on / track energy for. The surroundings are everything else that can interact with the system.

5.On a system schema, when do you draw a solid line between two objects, and when do you draw a dashed line?

Model answerSolid line = internal interaction — both objects are inside the chosen system. Dashed line = external interaction — it crosses the system boundary, connecting to something outside the system.

6.What does the size of an energy pie (the whole circle, not a slice) represent? What happens to that size if energy is transferred into or out of the system?

Model answerThe size of the whole pie represents the total amount of energy stored in the system. If energy is transferred OUT of the system, the pie gets SMALLER; if energy is transferred INTO the system, the pie gets BIGGER.

System Schema Practice

For each situation: list the interactions, then sketch a schema in the pad — dashed boundary around the system, solid lines inside it, dashed lines crossing it. Compare against the model when you're done.

1.A ball rests on a table. The system is the ball and the earth (the table is NOT in the system).

Interactions:

Model schema

2.A skater at rest pushes off a wall and glides away. The system is the skater ONLY (not the wall, not the earth).

Interactions:

Model schema

3.A magnet pulls a paperclip across a table toward it. The system is the magnet and the paperclip (the table and the earth are NOT in the system).

Interactions:

Model schema

Energy Pie Chart Practice

Drag the sliders to build each pie so the fractions match the situation. The dashed circle is the maximum possible size; an unfilled wedge means the pie hasn't grown that far yet. Reveal the model when you want a check.

1.A ball is thrown straight up. System = ball + earth. Position A: just after leaving your hand, low and moving fast. Position B: at the peak height, momentarily at rest.

Model answerPosition A: mostly Ek, a little Eg (already a bit off the ground). Position B: 100% Eg (all motion has become height). Same total pie size throughout — nothing leaves the ball+earth system.

2.A cart is released from rest at the top of a frictionless ramp. System = cart + earth + ramp. Position A: at the top, at rest. Position B: at the bottom, moving fastest.

Model answerPosition A: 100% Eg. Position B: 100% Ek. Same total pie size throughout.

3.A block sits against a compressed spring, then is launched up a frictionless incline. System = block + spring + incline + earth. Position A: block at rest against the fully compressed spring. Position B: block partway up the incline, still moving, no longer touching the spring.

Model answerPosition A: 100% Eel. Position B: a mix of Eg + Ek (Eel = 0 — the block has left the spring, and has gained both height and speed). Same total pie size as A.

4.Cart A (moving) collides with stationary Cart B and they stick together, moving off slower than Cart A's original speed (a perfectly inelastic collision). System = both carts. Position A: the instant before the collision. Position B: the instant after.

Reflection: is the total pie the same size in A and B? Why or why not?

Model answerNo — the pie shrinks. This is a perfectly inelastic collision, so some of the kinetic energy converts to Etherm and Esound at the moment of impact and leaves the cart-and-cart system (unless those forms are explicitly included).

Multiple Choice

Click an answer. It locks in and shows the correct choice — your score tracks at the top of the page.