space travel possible (1 Viewer)

[clever angel]

hi

i really don't know how to answer this q'n: a planet is 5 light yrs away form earth. current velocites are 20000km/hr. will a spacecraft able to reach the planet in a human lifetime . explain with a numerical argument?

thankxxx in advance

 

[香港!]

hi

i really don't know how to answer this q'n: a planet is 5 light yrs away form earth. current velocites are 20000km/hr. will a spacecraft able to reach the planet in a human lifetime . explain with a numerical argument?

thankxxx in advance

Light year, by definition from www.dictionary.com is:
"The distance that light travels in a vacuum in one year, approximately 9.46 trillion (9.46 × 10^12) kilometers..."
If current velocities are 20000km/hr then it will take 4.73 x 10^8 hrs to travel the distance of one light year.
There are approx. 24hrs a day so that's approx. 19.7 x 10^6 days.
Taking 365 days per year, then that's about 53995 years.
Clearly we don't survive that long and the spacecraft will not be able to reach the planet in a human lifetime.

 

[richz]

they wont expect us to know that light travels 9.46 * 10^12 km in one year right???

 

[香港!]

^dun think we need to know that lol

 

[helper]

they wont expect us to know that light travels 9.46 * 10^12 km in one year right???

You could be expected to calculate it from v=d/t but it is unlikely.

 

[Riviet]

At least know how to work it out using speed of light and the given time.

 

[DeanM]

k heres my answer... ( i just typed this out, but my browser screwed up )
k... here we go again..

the speed of light is 3.8 x 10^8 m/s , but we have the space craft going at 20 000 km/h , first lets convert this 20 000 km/h to m/s.. by dividing by 60, so 20 000 / 60 = 333, so the space craft travels 333 metres every second.. therefore, in one light year... 3.8 x 10^8 / 333... therefore it takes 1141414 yrs to 'reach' the distance of 1 light yr , so to reach 5, it is 1141414 x 5 = 5705705 yrs.. it seems very large... not sure if its correct, what do you's think ??

 

[Riviet]

k heres my answer... ( i just typed this out, but my browser screwed up )
k... here we go again..

the speed of light is 3.8 x 10^8 m/s , but we have the space craft going at 20 000 km/h , first lets convert this 20 000 km/h to m/s.. by dividing by 60, so 20 000 / 60 = 333, so the space craft travels 333 metres every second.. therefore, in one light year... 3.8 x 10^8 / 333... therefore it takes 1141414 yrs to 'reach' the distance of 1 light yr , so to reach 5, it is 1141414 x 5 = 5705705 yrs.. it seems very large... not sure if its correct, what do you's think ??

You got the conversion of km/h to m/s wrong, here's a trick: if you wanna convert anything that's in km/h to m/s, just divide by 3.6. By doing this you are dividing by 60 then 60 again to convert to seconds and dividing by 1000 to convert to metres.
So 20000km = 20000/3.6 m/s
=5556m/s
=5.556km/s
And isn't speed of light 3x10⁸m/s?
Anyway 1 light year=3x10⁸x60x60x24x365/1000
=9.46x10¹²km
.: 5 light years =5x9.46x10¹²
=4.73x10¹³km
.: the planet is approximately 4.73x10¹³km away from earth.
.: time=4.73x10¹³ / 5.556
=8.5x10¹² seconds
=8.5x10¹² / 60 / 60 / 24 / 365 years
=269534 years

 

[DeanM]

so besides thats mistake... the rest made sense ?? when i came up with that answer i thought it was alot... nice pick up Rivient