wunder beta

🍎 How does gravity work?

Connect falling apples, curved spacetime, orbits, tides, and cosmic structure through gravity’s universal reach.

lessons

~20 min

to learn

🔬 Science

subject

Adults

level

Start the course →

What you’ll learn

What falls and why it mattersDistinguish mass, weight, free fall, and local g.Gravity is universal attraction. Mass is intrinsic; weight is force in a field; free fall equalizes acceleration when drag is gone.
Newton’s law of gravitationState inverse-square attraction and orbital free-fall intuition.Force grows with mass product and falls as 1/r². Orbits are sideways free fall; many bodies superpose pulls.
Orbits, weightlessness, and tidesExplain weightlessness, orbital speed, tides, and escape as energy in a well.Floating in orbit is shared free fall. Tides are gravity gradients. Escape means climbing out of a potential well.
Einstein’s curved spacetimeContrast Newtonian force with geometric gravity and name key tests.GR curves spacetime; light bends and clocks shift. Newton remains excellent for everyday weak fields.
Gravity across the cosmosApply gravity ideas to stars, black holes, galaxies, and waves.Stellar structure is gravity versus pressure. Black holes are extreme curvature. Waves and galactic dynamics extend the story.

Questions this course answers

What is the difference between mass and weight?

Mass is intrinsic; weight depends on the local gravitational field (and accelerating frames).

Match each term to its meaning

Free fall is unsupported motion in a gravitational field; g quantifies local field strength as acceleration; universality is the global rule.

Complete the inverse-square idea

Force scales as 1/r², so doubling r multiplies force by 1/4.

In Newton’s picture, why can a planet orbit instead of falling straight into the Sun?

Orbital motion is free fall with enough sideways velocity that the trajectory curves around the central body.

Why do astronauts float in the space station if Earth’s gravity is still strong there?

Orbital free fall means astronaut and station accelerate together; weight sensation requires a support force, not the absence of Earth’s gravity.

Order these from stronger near-side pull idea to the ocean effect

Tides arise from gravity gradients; rotation cycles locations through the bulges.

Grounded in trusted sources

OpenStax University Physics — Newton’s law of gravitation, orbits, and introductory general relativity notes
NASA educational pages on orbits, microgravity, and tides
LIGO/Virgo public education materials on gravitational waves (GW150914)
ESA / Hubble outreach materials on spacetime tests and black holes (public education level)

Every Wunder lesson is built from real, reputable sources — never invented.

Related Science courses

⚖️Balanced and Unbalanced Forces 🧲Contact and Non-Contact Forces Habitat connectionsHow do coastal wetlands connect habitats?Wetland adaptationHow do coastal wetlands adapt to climate change?Nursery habitatHow do coastal wetlands create nursery habitat?Water filterHow do coastal wetlands filter and transform water?Tidal channelsHow do coastal wetlands create and maintain tidal channels?Connected food websHow do coastal wetlands feed connected food webs?

Wunder is a personalized learn-anything platform — tell it any topic and it builds a beautiful, fact-checked course in minutes, with narration, a knowledge check, and a college-style University track.

Browse more Science courses · All topics · Home