AST101_fall2011_lecture7_oct4_v1

AST101_fall2011_lecture7_oct4_v1 - Tides Tides Acceleration...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Tides Tides Acceleration of Gravity We found F g =G ME MR d 2 and F g = M R a g Hence, a g =G ME d 2 With d = RE , a g =9.8 m/s 2 Earth: 9.8 m/s2 Tides in orbit around Earth Tides a head = G afeet = G ME =8.6115701 m / s ( 6800 km)2 ME =8.6115758 m / s 2 ( 6800 km −2 m ) 2 2 Δ a = 0.0000057 m / s 2 Note: you do not have to reproduce this! Tides around Jupiter Tides (M=0.001 Msun, R=0.1 Rsun) a head = G afeet = G 0.001 M sun ( 105 km )2 0.001 M sun 7 = 1.32666× 10 m / s 6 =1.32693 ×10 m / s 5 2 ( 10 − 10 km ) Δ a = 2.7×103 m / s 2 2 2 Shoemaker-Levy 9 Shoemaker-Levy Shoemaker-Levy 9 Shoemaker-Levy Shoemaker-Levy 9 Shoemaker-Levy Morbid Quiz (not for marks) Morbid If you want to see a black hole from the inside, If is it better to pick a stellar-mass one or is a supermassive black hole? A stellar mass one (~Msun, 3 km) A A supermassive one supermassive (~107 Msun, 3x107 km) (~10 B It doesn't matter C I have no clue D Tides in orbit around a black hole Tides (M=1 Msun, R=3.0 km) R=3.0 a head = G afeet = G M sun 13 2 13 2 =1.47407× 10 m / s ( 3 km )2 M sun = 1.47604 × 10 m / s 2 ( 3 km −2 m ) Δ a= 1.97× 1010 m / s 2 Tides in orbit around a supermassive black hole Tides (M=107 Msun, R=3.0x107 km) 7 a head = G afeet = G 10 M sun 6 2 6 2 = 1.47407 ... × 10 m / s 7 2 ( 3 × 10 km ) 107 M sun = 1.47407 ...× 10 m / s 7 2 ( 3 ×10 km− 2 m ) Δ a = 0.0001 m / s 2 Clicker Quiz (1 min) Clicker How often is it high tide? Every 24 hours A Every 24 hours 50 minutes B Every 12 hours C Every 12 hours 25 minutes D Tides Moon Sun (far away) Spring and Neap Tide Clicker Quiz (1 min) Clicker How often is it Spring tide? Every half a month Every month A Every month B Every quarter year C Every half a year D Every year E Bay of Fundy Bay Tidal Drag Fg Clicker Quiz (2 min) Tidal Drag What happens to the Moon's orbit due to the tides?Wh The distance decreases and the month shortens A The distance decreases and the month lengthens B The distance increases and the month shortens F g C The distance increases and the month lengthens D Lunar Ranging Clicker Quiz (2 min) Lunar Ranging As the Moon moves out, As What happens to Earth? What It spins down and cools down A It spins down and heats up B It spins up and cools down C It spins up and heats up D Positioning Historical Eclipses Prediction vs Observation Eclipse Timing Length of Day Clicker Quiz (1 min) Length of Day What is the final state tides lead to? The moon is ejected A The moon crashes on Earth B Day and month become the same C No final state can be reached D Clicker Quiz (1 min) Length of Day What is the final state tides lead to What Phobos month for Mars's moon Phobos? =0.31 Mars days for The moon is ejected A The moon crashes on Mars B Day and month become the same C No final state can be reached D ...
View Full Document

Ask a homework question - tutors are online