[thedoc (OP)]

Jody Nakin asked the Naked Scientists:

Hi there Guys, my 8 year old weighs 22kgs, I am am able to pick her up and carry her very easily. However after falling asleep in front of the telly, when taking her to bed, I am convinced she weighs 50 kilos!

Why is this, am I being lazy and just complaining for no reason?

What do you think?

[alancalverd]

The term "dead weight" originated from observation. Most adults can carry another conscious adult of the same build, but it takes four people to lift a patient off an operating table, and a dead dog is a lot more difficult to move than a live one.

I think conscious animals tense their muscles and move their limbs when lifted, so as to keep the center of mass above the lifting point(s) and distribute the torque moments evenly between them, making it easier for the lifter to control the load.