APAS 1120 SECTION 001
 

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3. Orbit of Pluto is 39AU = 39x1.5x10¹³cm = 6x10¹⁴cm. Scale factor is:

i) human 200cm ® 200/3x10¹³ = 6x10^-12cm
ii) Earth 6000km ® 6x10⁸/3x10¹³ = 2x10^-5 cm
iii) Sun 1AU ® 1.5x10¹³/3x10¹³ = 0.5cm
iv) Star 1pc ® 3x10¹⁸/3x10¹³ = 10⁵ cm = 1km
v) MilkyWay 10000pc ® 3x10²²/3x10¹³ = 10⁹ cm = 10,000km
vi) M31 10⁶pc ® 3x10²⁴/3x10¹³ = 10¹¹ cm = 10⁶km
vii) Universe 5billion pc ® 1.5x10²⁸/3x10¹³ = 5x10¹⁴ cm = orbit of Pluto!

4. Must go 6x10¹⁴cm in 7years.

7years = 7 x 3x10⁷ seconds = 2.1x10⁸ s