Q 01/05

Which quantity quadruples when a car doubles its speed?

A) Kinetic energy

B) Inertia

C) Thermal energy

D) Sound energy

Answer · why

A) Kinetic energy

Kinetic energy is half the mass times the speed squared, so doubling speed gives four times as much; Gravesande showed it by dropping weights into cla...

Q 02/05

What causes thunder, the rumble or crack that follows 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 spanned about three Earths in the late 1800s, some 40,000 km; by 2014 Hubble measured it at about 16,500 km, little wider than one ...

Q 04/05

Which phase change, the reverse of sublimation, makes frost by turning water vapour straight into ice?

A) Condensation

B) Freezing

C) Deposition

D) Evaporation

Answer · why

C) Deposition

Deposition skips the liquid stage entirely, and it is how hoar frost builds its ice crystals on leaves and windows during cold, clear 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.