Longer days and slower planets

could i increase the length of a day?
its pretty easy to do. Stretch your arms wide and spin yourself in the opposite sense than in the direction in which the earth is rotating and suddenly jump and stop spinning. if you were spinning really fast, and you are really heavy the difference the length of day will increase by 10^-37th of a second.

if you take a disk 1 km in radius, and weighing a 1000 tons, and start spinning it at like 50 radians per second and then lift it off the face of the planet, you'll do a little better, you'll have increased the length of day by 10^-18th of a second.

of course the assumption is that there is no tiny meteorite, pebble rather, that is hitting the earth somewhere else in a way that it can cancel out your action....

i wonder how much force superman was applying on the earth by taking off at that tremendous velocity! if he's as heavy as the rest of us(bad assumption since he wouldnt be able to fly) but takes off, say, at half the speed of light, and then he's a little sluggish so takes a second to actually take off, then he's applying a force enough to speed up the earth by 10^-25th of a second if he's headed in the opposite direction. he'll slow it down by the same amount if he heads in the same direction the earth is headed...

if he has to take off 10^25 times and take off in the same direction everytime, and he lands very gently, the length of a day will change by a second.

guess he is isnt super after all...