Q 01/05

Which quantity, half the mass times the speed squared, quadruples when a car doubles its speed?

A) Kinetic energy

B) Thermal energy

C) Sound energy

D) Chemical energy

Answer · why

A) Kinetic energy

Kinetic energy rises with the square of speed, so doubling speed gives four times as much; Gravesande showed this by dropping weights into clay, where...

Q 02/05

What causes thunder, the rumble or crack that reaches you a few seconds after a flash in a storm?

A) Clouds crashing into each other

B) Lightning rapidly heating air

C) Ice crystals shattering in clouds

D) Wind whistling through cloud gaps

Answer · why

B) Lightning rapidly heating air

Lightning rapidly heating air is the whole story: the sudden jump in temperature and pressure makes the air along the bolt expand explosively, and tha...

Q 03/05

Which Jupiter storm, watched since 1831, has been shrinking for a century from three times Earth's width?

A) Great Dark Spot

B) Oval BA

C) Great Red Spot

D) Great White Spot

Answer · why

C) Great Red Spot

The Great Red Spot was about three times Earth's diameter a century ago, when it stretched some 40,000 km across, and nobody is sure why it keeps shri...

Q 04/05

Which phase change makes frost by turning water vapour straight into ice, skipping the liquid stage?

A) Sublimation

B) Condensation

C) Freezing

D) Deposition

Answer · why

D) Deposition

Deposition is sublimation run backwards, and it is how hoar frost grows its feathery crystals on leaves and windows during clear, cold nights.

Q 05/05

Which afternoon wind blows from the ocean onto the coast because land warms faster than water?

A) Sea breeze

B) Land breeze

C) Trade wind

D) Monsoon

Answer · why

A) Sea breeze

A sea breeze flips after sunset into a land breeze, because dry land also cools faster than water once the Sun stops shining on it.