Letter: Weighty matters
Tuesday 09 March 1999
Sir: Dr Anthony Egan's letter (3 March) suggests that astronauts are "weightless". If they were they would travel away from the earth in a straight line. It is their weight (somewhat less than their weight at the earth's surface) which provides the centripetal force which keeps them travelling in a circular orbit around the earth. Their spacecraft is behaving in the same way, so in relation to the spacecraft they appear weightless.
His idea that mass is "how much stuff there is" is not wholly incorrect but I think that Newton would have preferred the idea of mass being a measure of the resistance of an object to having its motion changed. Which is why Brussels's use of the word mass is appropriate in the context of bringing a trailer or caravan to a stop in a safe distance.
Little Walsingham, Norfolk
ReviewThese heroes in a half shell should have been left in hibernation
Sek, k'athjilari! (That’s “yes, definitely” to non-native speakers).TV
Arts & Ents blogs
- 1 Indian footballer Peter Biaksangzuala dies after injuring spine doing somersault celebration
- 2 Jack the Ripper: Scientist who claims to have identified notorious killer has 'made serious DNA error'
- 3 Drink alcohol and eat meat to improve male fertility - but cut down on coffee, studies suggest
- 4 Kentucky gang rape: 15-year-old boy left in critical condition after sexual attack by group at party
- 5 Lynda Bellingham dead: Loose Women presenter dies after battle with colon cancer
Breaking Bad season 6 is still not happening
Doctor Who, Flatline - review: Clara isn’t half bad as the Time Lord
Downton Abbey review series 5, episode 5: Period drama falls disappointingly flat
Star Wars Episode 7 has almost finished filming
X Factor 2014 results: Chloe Jasmine and Stephanie Nala sent home
Cameron is warned 'no possibility' of UK reducing immigration and that bid to bring in quota on migrant workers would be illegal
Sorry Judy Finnigan – Ched Evans is no less sickening than an alleyway rapist
Residents should throw a street party and mix with immigrant neighbours, councils told
Workers 'could be forced to pay £5 a week' to get benefits
Russell Brand threatened with arrest after filming outside Fox News headquarters
Amal Alamuddin calls for the return of the Elgin Marbles from Britain: 'Injustice has persisted for too long'