Drag the slider. Watch gravity weaken, storms grow, and the equator bulge.
Right now Earth spins at about 1,670 km/h at the equator. You don't feel it because everything on the surface spins with you. But spin has consequences. The faster you go, the more centrifugal force pushes outward. At the equator, you already weigh about 0.3% less than you do at the poles. That sounds tiny. But if you spin faster, it stops being tiny.
If a day were 12 hours, the equator would bulge more. The planet would become visibly squashed. Your weight at the equator would drop by about 2%. Storms would spin faster because the Coriolis effect scales with rotation. Hurricanes would become almost constant. Weather would be violent.
If a day were 4 hours, you would weigh about 10% less at the equator. People living near the equator would feel noticeably lighter. Airlines would fly west just to get a boost. But the weather would be unlivable. Clouds would form spiral bands that never break. Rain would fall in sheets for months. Coastal cities would flood because the equator bulge pulls water toward the middle.
At about 1.4 hours per day, centrifugal force at the equator cancels gravity entirely. You would be weightless. You could jump and not come down. The planet itself would start to fall apart. Rocks at the equator would lift off into space. This is not a scenario. This is the breakup speed. Earth would never survive it.
Yes. About 0.3% less. A 70 kg person weighs 69.8 kg at the equator and 70.2 kg at the poles. The difference is small but measurable. Scales have to be calibrated for location.
When centrifugal force equals gravity at the surface. For Earth, that's about a 1.4-hour day. At that point, rocks at the equator float off. The planet literally tears itself apart. No known planet survives its breakup speed.
Yes. Your circadian rhythm is roughly 24 hours. If the day were 12 hours, you'd get one light, one dark, then another light in 12 hours. Your sleep schedule would break. Shift workers already know this pain.
Mars has a day of 24.6 hours. Almost exactly Earth's. That's why Mars rovers can run on nearly human schedules. A sol is one Mars day. It's 40 minutes longer than an Earth day.