going by einstein's e=mc^2, how much energy is a 100lb block of ice?

Question

i forget how to convert weight into mass. how much mass does a 100lb block of ice have? is it 100/9.8 or something? anyway, say it has mass m. how do you multiply this number by the speed of light? and then to multiply it again by the speed of light. what number do you use for the speed of light? does it matter if you use metric or not? the speed of light is a distance over time number. what is the distance measured in, and what unit of time makes his equation true?

Answer 1

It comes out 4.082*10^18 joules. In the English system, the mass of the ice is the same as the weight of the ice, so the 100 lb of ice is 100/2.2 kg of ice or 45.4 kg. The speed of light is 3*10^8 meters/sec

The result is 9*45.4*10^16 kg*m^2/sec^2. A kg*m^2/sec^2 is one joule.

Answer 2

0...the block of ice isn't moving. E=mc2 only concerns moving objects. The speed of light is approx 186,000 miles per second. Light will travel approx 6 trillion miles in a year.His equation is only a theory, so it may or may not be true.He was thinking the faster an object moves, the more energy it takes to move it...and as it increases in speed, it will also increase in mass the faster it goes. So in theory, nothing solid can reach the speed of light as it's mass will have doubled before it reaches the speed of light. A space ship would explode long before it got that fast.

Answer 3

I think you have to use molecular mass for water. And estimate how many water molecules are in 100lbs of ice block. I think 'mass' in physics is different than 'weight'. So, phrase 'I weigh 140lbs' may not be same as 'my mass is 140lbs', I don't think.

Answer 4

First, the ice is indeed moving. It moves as the earth rotates on its axis and as it revolves around the sun.

Second, the relevent equation applies to all matter, not just moving matter.

The first answer is correct. The second answer is stupid.