Umkhangeli zincwadi

1. 1

   Uxinzelelo lweNewton

   • Newton's gravity · 12 min

     One law explains falling apples, the Moon's orbit and the path of every planet. Fire Newton's cannon and find out how.

2. 2

   Imithetho kaKepler

   • Kepler's laws · 14 min

     Three rules found from careful observations in the early 1600s still describe every orbit, from moons to exoplanets.

3. 3

   Izinto zobumnini Zolwaleko...

   • Orbital elements · 14 min

     Six numbers pin down any orbit in space: its size, shape, tilt, orientation and where the body is on it.

4. 4

   Isantya sokuhamba: i-equation ye-vis-viva

   • Orbital speed: the vis-viva equation · 12 min

     One short equation gives the speed of anything in orbit at any point, if you know how far it is and the size of its orbit.

5. 5

   Isantya sokuphuma

   • Escape velocity · 12 min

     How fast do you need to go to leave a world for good? And why rockets do not actually need to reach it at the surface.

6. 6

   Kutheni i-orbit iwela

   • Why an orbit is a fall · 10 min

     Astronauts float not because there is no gravity up there, but because they are falling all the time, and missing.

7. 7

   Ukufikelela kwi orbit: ujikelezo lokutsala

   • Reaching orbit · 12 min

     Why rockets go up for only a few seconds, then spend ten minutes going sideways: the gravity turn, staging and orbital insertion.

8. 8

   I-rocket equation ne delta-v

   • The rocket equation and delta-v · 12 min

     Why rockets are mostly fuel, why they come in stages, and the one equation behind every mission's budget.

9. 9

   Uthutho lweHohmann

   • Hohmann transfers: changing orbits · 12 min

     To go higher you speed up, and then you arrive slower. The two-burn manoeuvre that moves satellites from low orbit to geostationary orbit.

10. 10

    Qala iifestile

    • Launch windows: the road to Mars · 12 min

      You cannot aim at Mars, only at where Mars will be in eight months. Why Mars missions leave every 26 months, all at once.

11. 11

    Ukufaka i-orbit: ukuqwalaselwa

    • Orbital insertion: getting captured · 12 min

      Arriving at a planet is the most dangerous minute of a mission: one burn decides whether you stay or fly past forever.

12. 12

    Uxinzelelo lwe-gravity lunceda

    • Gravity assists: the free slingshot · 12 min

      How Voyager, Cassini and New Horizons stole speed from planets, and why it never breaks the conservation of energy.

13. 13

    Iimpawu ze-Lagrange

    • Lagrange points: balance in the sky · 11 min

      Five places around every pair of worlds where a spacecraft can ride along for free, and why the James Webb Space Telescope lives at one of them.

14. 14

    Umhla wokudibana nokungena

    • Rendezvous: catching the space station · 11 min

      To catch something ahead of you in orbit, you drop lower and go slower-looking but faster. The counter-intuitive art of meeting in space.

15. 15

    Ukuya ekhaya: ukubuyela ngaphakathi

    • Coming home: reentry · 11 min

      A small push slows a spacecraft by a hundred metres per second, and the air takes care of the other 7.8 kilometres per second, as a fireball.

16. 16

    Iiplothi zePorkchop

    Iyafika

17. 17

    Iiplanethi

    Iyafika

Izixhobo kunye neengcebiso zisebenzisa iimodeli ezilula zokufunda kuphela. Akufanele zisetyenziswe ukuqhuba, ucwangciso lwemikhosi okanye nayiphi na intlawulo yokusebenza. Iziqinisekiso azihlawulwanga kwaye azigunyaziswanga. Funda uxanduva lokungasebenzisi imixholo yoqeqesho