Floating and Flying

Question 1 · multiple choice

A sealed empty plastic bottle floats mainly because its average density is…

Lower than water's Higher than water's Higher than steel's Equal to stone's

Question 2 · multiple choice

A parachute works by increasing…

Air resistance Earth's gravity The falling distance required The person's mass

Question 3 · multiple choice

A clay lump sinks, but the same clay shaped into a boat can float. Why?

Its clay becomes lighter chemically It displaces more water before sinking Its material becomes waterproof only then Water stops exerting pressure

Question 4 · multiple choice

A hot-air balloon rises when its inside air is heated because that air becomes…

Unable to exert pressure Heavier per litre A different chemical element Less dense than surrounding air

Question 5 · true false

True or false: An aircraft's wings require perfectly still surrounding air to generate lift.

True False

Question 6 · multiple choice

Why are submarine ballast tanks filled with water to dive?

To shrink the ocean To increase average density To make the hull transparent To create upward lift

Question 7 · multiple choice

A helium balloon shrinks in a cold room at similar outside pressure. Its gas…

Turns into ordinary air Becomes a solid immediately Occupies less volume Gains extra atoms

Question 8 · multiple choice

Which connects a fish's swim bladder and a diver's buoyancy jacket?

Keeping all water outside the body Producing oxygen from salt Controlling buoyancy with gas Measuring ocean depth directly

Question 9 · multiple choice

A hydraulic lift uses the same pressure on a larger output piston. What increases?

Energy without any input Pressure without any input The liquid's compressibility Output force

Question 10 · multiple choice

Water presses harder on the bottom of a tall tank than near its top because…

More water lies above it Water loses mass as it rises The bottom water is always saltier The tank blocks sunlight