Why is it harder to hold a dumbbell with a stretched arm than with a flexed one?

[userEWJKDQRT6DO]

Say I hold a dumbbell in a 90 degree angle between the bicep and the forearm. The more I lower the dumbbell and stretch the arm, the harder it is to hold the weight. Why?

I think it has something to do with levels, but my physics is not that great.

[Heisman2]

You need to be more descriptive with your arm position. If you are standing with your upper arm by your side then you will be using your biceps a lot to keep the arm flexed at 90 degrees while if you have your arm straight you won't use your biceps at all and keeping your arm straight will make it easier. If you have your arm directly in front of you then when you have your arm bent the load will be closer to your shoulder then when your arm is straight, and in that case the lever does matter and it will be harder with the arm straight given the greater distance.

[paulinkansas]

The physics equation is Torque = Force x Moment Arm.

Here's another one that makes me a lot of money: Pressure x Volume = N x Gas Constant x Temperature.

[air2fakie]

Think it depends on what you're holding. It's easier to hold a bag of groceries with a stetched arm than a flexed one.

Going to try with a cup of coffee in a few minutes and will report back.

[Casca]

The up position of a bicep curl (guessing that is what you mean) the weight is resting on your palm. You don't even have to grip it if you don't go past 90 . At the bottom, it's all grip.