Useless Trivia? Need help on tough questions:

[packerz4]

Hi there, am helping a frieind with some questions for an Environmental Geology class... haven't been able to figure a few things out:

1. HOW MUCH ENERGY DOES IT TAKE TO MELT A CUBIC KILOMETER OF ICE?

2. THE ENERGY REQUIRED TO LIFT A MASS (m) TO A HEIGHT (h) IS mGh, WHERE G IS THE EARTH'S GRAVITATIONAL ATTRACTION AND EQUALS 9.8m/SECOND SQUARED. HOW MUCH CUBIC KILOMETERS OF ROCK COULD YOU LIFT TO A HEIGHT OF 1 KM WITH 3.8 X 10^24 JOULES/YEAR?

SO OK YOU SUPER SMART PEOPLE ON THIS SITE, HELP ME OUT...

TK

I DON'T REMEMBER COLLEGE BEING THIS HARD WHEN I WAS THERE?


TK

[doug hodder]

So how fast do you want to melt it? low energy, slow melt... lots of energy, lots of melt...Al Gore seems to have all the answers...drop him a PM... Doug

[Unkl Ron]

1. HOW MUCH ENERGY DOES IT TAKE TO MELT A CUBIC KILOMETER OF ICE?

First calculate the energy to melt 1 cubic meter of ice..

Density of Ice 916.7 kg per m^3..
Heat of Fusion 334 kJ per kg.

916.7kg m^3 *334 kJ/kg = 3.06e+5 kJ m^3
Scaling up to km^3.. multiply by 1000^3 or (+1e9)
3.06e+5 *1e+9 = 3.06e+14 kJ km^3

Someone else can work out Q2 - I'm goin campin.

[packerz4]

1. HOW MUCH ENERGY DOES IT TAKE TO MELT A CUBIC KILOMETER OF ICE?

First calculate the energy to melt 1 cubic meter of ice..

Density of Ice 916.7 kg per m^3..
Heat of Fusion 334 kJ per kg.

916.7kg m^3 *334 kJ/kg = 3.06e+5 kJ m^3
Scaling up to km^3.. multiply by 1000^3 or (+1e9)
3.06e+5 *1e+9 = 3.06e+14 kJ km^3

Someone else can work out Q2 - I'm goin campin.

WOWZA! THANKS'S UNKL RON! YOU BLOW MY MIND! I KNEW SOMEONE WOULD COME THROUGH FOR ME.

TK

[Nitetimes]

Hi there, am helping a frieind with some questions for an Environmental Geology class... haven't been able to figure a few things out:

2. THE ENERGY REQUIRED TO LIFT A MASS (m) TO A HEIGHT (h) IS mGh, WHERE G IS THE EARTH'S GRAVITATIONAL ATTRACTION AND EQUALS 9.8m/SECOND SQUARED. HOW MUCH CUBIC KILOMETERS OF ROCK COULD YOU LIFT TO A HEIGHT OF 1 KM WITH 3.8 X 10^24 JOULES/YEAR?


TK

4

[raprap]

1) 1 km or ice melting ---Ice has a specific gravity of about 0.92 and water has a heat of fusion 0f about 336 kJ/kg.

1 km^3 ice*(1000 m/km)^3*1000 kg/m^3*0.92*336 kJ/kg=3.1x10^14 kJ.

2) misleading question, 3.8*10^24 J/yr is power term not an energy term---power is energy over time.

However you can determine how fast the rock is rising by assuming the rock has an average density with a sg~2.8. Then 1 km^3 of rock has a mass of 2.8X10^12 kg/km^3 and the power term is (in term of seconds) 9.1x10^16 J/s. Now the upward velocity of 1 km^3 rock is
vh(km/s)=[9.1X10^16 J/s]/[9.8 m/s^2]/[2.8X10^12 kg]=3.3x10^(-9) m/s
since 1J=1 mkg/s^2

In terms of years and km then 2.8X10^24 J/yr can lift 1 km^3 of rock at a rate of 1.1x10(-4) km/yr (its not going to win at Daytona).

Rap

[raprap]

1 km^3 of rock at a rate of 1.1x10(-4) km/yrRap

Actually that's about 4 inches per year straight up---on a geologic scale that almost a mach speed--to put it in perspective you could build a small Mt Everest from sea level in in less than a 100,000 years. (The real Mt Everest is much larger than 1 km^3)

Rap

[packerz4]

1 km^3 of rock at a rate of 1.1x10(-4) km/yrRap

Actually that's about 4 inches per year straight up---on a geologic scale that almost a mach speed--to put it in perspective you could build a small Mt Everest from sea level in in less than a 100,000 years. (The real Mt Everest is much larger than 1 km^3)

Rap

Thanks Rap! You and Unkl Ron blow my mind... funny part is you could totally be bull-shi**ing me, and I wouldn't have a clue. But your answers seem to make sense... I'm sure I learned how to calculate such a thing at some point in college, but as soon as that exam was over, I cleared out the space in my brain for other stuff. The fact that you guys know how to calculate this stuff is too cool, and freaky all at the same time.

but you're teardroppers, so i love ya NO matter what.

thanks again!

tk

[packerz4]

Hi there, am helping a frieind with some questions for an Environmental Geology class... haven't been able to figure a few things out:

2. THE ENERGY REQUIRED TO LIFT A MASS (m) TO A HEIGHT (h) IS mGh, WHERE G IS THE EARTH'S GRAVITATIONAL ATTRACTION AND EQUALS 9.8m/SECOND SQUARED. HOW MUCH CUBIC KILOMETERS OF ROCK COULD YOU LIFT TO A HEIGHT OF 1 KM WITH 3.8 X 10^24 JOULES/YEAR?


TK

4

AWESOME ANSWER NITETIMES!

[Nitetimes]

Hi there, am helping a frieind with some questions for an Environmental Geology class... haven't been able to figure a few things out:

2. THE ENERGY REQUIRED TO LIFT A MASS (m) TO A HEIGHT (h) IS mGh, WHERE G IS THE EARTH'S GRAVITATIONAL ATTRACTION AND EQUALS 9.8m/SECOND SQUARED. HOW MUCH CUBIC KILOMETERS OF ROCK COULD YOU LIFT TO A HEIGHT OF 1 KM WITH 3.8 X 10^24 JOULES/YEAR?


TK

4

AWESOME ANSWER NITETIMES!

Hey, ya gotta keep it simple. Amazing how close I got without actually calculating anything tho huh?

[Bobgorilla]

Thats not trivia thats MATH
"Trust me Roy, I've played this game before, One of the answers is AnnMargret"