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Card 1.1 Companion

Card 1.1 Worksheet

Optional paper version of the Card 1.1 written artifact. Fill it out by hand and bring it to your oral check instead of sharing a Google Doc.

Name: Date:

The two-number contest

An object sinks, floats, or hovers depending on two numbers: its own pulling down, and the weight of the water it pushing up. Exactly equal, the object is at buoyancy.

Before you touch anything: predict

1. A sealed object hovers, neutrally buoyant, at 1 meter deep. We move it to 3 meters and release it. Does it stay, rise, or sink?
   Why?

2. Does your answer change if the object is a sealed rigid box instead of a soft air-filled bag?
   Why or why not?

Bench challenge: your parts

For each part: weigh it, measure its volume by water displacement in the 9-inch bin, calculate buoyant force (volume × 1 g/cm³) and net force (buoyant force minus weight), predict, then test it in the bin.

Part	Weight (g)	Volume (cm³)	Buoyant force (g)	Net force (g)	Prediction	Actual

Which part surprised you most, and why?

Two sentences

Why does a steel ship float? Use the word “displaces.”

One sentence

Our float (Ebirah) changes its buoyancy without adding or removing any weight. Based on today, what MUST it be changing instead?