Below is the full Quizmo quiz devoted to the theme "Gravity": each question, its four options, the correct answer highlighted and, where available, its source. A chance to brush up on your general knowledge and then test what you know.
▶ Play today's quizWhat happens to a dropped object when gravity pulls it toward Earth?
Source: Gravity always pulls objects toward Earth's center, which is why everything dropped heads straight down.
Which scientist is most famously linked to the law of universal gravitation?
Source: Newton published his law of gravitation in 1687, though the falling-apple story may be more legend than fact.
Which force causes ocean tides to rise and fall each day?
Source: The Moon's gravitational pull tugs the oceans, bulging the water and producing two high tides daily.
What ultimately holds planets in orbit around the Sun?
Source: The Sun's immense gravity bends each planet's path into an orbit instead of letting it fly off in a straight line.
On which body would an astronaut feel the strongest surface gravity?
Source: Jupiter's surface gravity is about 2.5 times Earth's, so a person there would feel crushingly heavy.
Why do astronauts appear to float inside an orbiting space station?
Source: They are constantly falling toward Earth while moving sideways fast enough to keep missing it, creating weightlessness.
Compared to Earth, how strong is gravity on the Moon's surface?
Source: Lunar gravity is roughly one sixth of Earth's, which is why Apollo astronauts could bounce across the surface.
In a vacuum, which falls faster: a feather or a hammer?
Source: Without air resistance all objects accelerate equally, a fact Apollo 15 famously demonstrated live on the Moon.
Roughly how fast does Earth's gravity accelerate a falling object each second?
Source: Earth's gravity adds roughly 9.8 metres per second of speed every second of free fall.
A skydiver eventually stops speeding up and falls at a steady rate. What is this called?
Source: At terminal velocity, air resistance balances gravity, so a skydiver stops accelerating at around 200 km/h.
Why does your weight change on the Moon while your mass stays the same?
Source: Mass is the amount of matter you contain, but weight is gravity pulling on that mass, so weaker gravity means less weight.
What name is given to the speed needed to break free of Earth's gravity?
Source: A rocket must reach about 11 km per second to escape Earth's gravity and never fall back.
Which 2013 space-survival film starring Sandra Bullock shares its name with the force?
Source: Alfonso Cuaron's film won seven Oscars and was praised for its eerily realistic depiction of weightlessness.
According to Einstein, what does a massive object actually do to cause gravity?
Source: Einstein reimagined gravity not as a pull but as the curving of spacetime that mass creates around itself.
What collapsed star has gravity so strong that not even light escapes it?
Source: A black hole's gravity is so extreme that beyond its event horizon nothing, not even light, can get back out.
Ripples in spacetime first detected in 2015 are known as what?
Source: LIGO detected gravitational waves from two merging black holes, confirming a prediction Einstein made a century earlier.
Which experiment did Galileo reportedly use to study how objects fall?
Source: Legend says Galileo dropped balls from the Leaning Tower of Pisa to show that weight does not change falling speed.
What boundary marks the point of no return around a black hole?
Source: Cross the event horizon and the black hole's gravity makes escape impossible, even at the speed of light.
Which spacecraft maneuver uses a planet's gravity to gain speed for free?
Source: A gravity assist slingshots a probe around a planet, stealing a bit of its orbital motion to fling the craft onward.
Where in a satellite's elliptical orbit does Earth's gravity make it move fastest?
Source: Gravity is strongest where the orbit is nearest Earth, so the satellite whips around fastest at that closest point.