# If the earth stopped spinning

1. Oct 13, 2005

### Pengwuino

What would be the gravitational effects on people if this happened? I figure gravitational force - centripetal force = 9.8m/s^2... so is the gravitational force much stronger then 9.8?

2. Oct 13, 2005

### JesseM

You can see here that the formula for the centripetal force is $$F = mv^2 / r$$, so the centripetal acceleration would be $$v^2 /r$$. Here, v is the circumference of the earth divided by the rotation period of the earth (assuming you're standing at the equator), or 2*pi*r/(86400 seconds) , so squaring this and dividing by r gives 4*pi^2*r/(7.46496*10^9 s^2) = 0.034 meters/second^2. So, if the earth wasn't rotating gravity would only feel about 1.0035 times as strong as it does now at the equator, not a noticeable difference.

3. Oct 13, 2005

### Pengwuino

Oh pff... guess i was wrong :D thanks!

4. Oct 13, 2005

### Chronos

Jesse has it right. The centripetal force due to earth's rotation is minor compared to gravity. The inertial force, on the other hand, might be worrisome were the earth to suddenly stop rotating. Buckle up. According to the Surgeon General, slamming into a mountain at ~1000 miles per hour can be hazardous to your health.