A cup of water

When one hold up a cup of water and ask how heavy is the water? People will answer 20g to 500g depending on how full and how big the cup is. Actually the exact or actual weight doesn't matter. It depend on how long you are holding it. Try holding it up with your hand for 1 minute, i am sure that it is isn't a problem. Hold it for 1 hour for sure you will feel tired and sore on your hands. Holding it for 1 day i am sure you can't even put up your hand on the next day. Not to say to hold it for few days, by that time i think there is a need to call an ambulance. No matter how long the cup is being hold, the weight is still the same but we our hand feels that it is getting heavier and heavier. Once there is burden on our shoulder we need to try to get rid of it as soon as possible or else it will get heavier until a stage that we will not be able to carry on. As for the glass of water when you feel tired you will tend to put it down a while before holding it back. this is the same as burden when we are tired of something, let it go a while, refresh ourselve, then start on again with a fresh mind to continue on as if we make the cup lighter by drinking the water inside it..