The earth takes exactly 24 hours for one full rotation calculate

1. Jun 25, 2012

sazzy

the speed of rotation of a point on the equator

the title is the only information I have been given to work out this questions and it relates to a2 phyics uniform circular motion and the answer is 465ms-1 I just cannot get it I know the eqautor must have something to do with it PLEASE HELP

Full calculations shown please!

the textbook gives equations speed = 2pi*r/T but I am not given radius and using the radius does not give the correct answer anyway

the closest I got was 471 ms-1 using pi/24*3600 and I just used pi because I am assuming because it asks along the equ I should use 180 degrees

2. Jun 25, 2012

gbaby370

If you're getting 471, it could just be a matter of how you're rounding some of the variables like pi or the radius of the Earth.

I used the exact same equation using the pi option on my calculator and for r, I used 6.378x10^6 and I got 463.82m/s.

Hope this helps!

3. Jun 25, 2012

D H

Staff Emeritus
The Earth takes 24 hours to make a full rotation with respect to the Sun. The Earth is also orbiting the Sun. This means it takes a bit less than 24 hours for that Earth to make a full rotation with respect to the stars. Another way to look at it is that the Earth rotates a bit more than 360 degrees in 24 hours. This extra little bit of rotation is what gives that answer of 465.1 m/s as opposed to the 463.8 m/s that gbaby370 obtained.

4. Jun 25, 2012

SammyS

Staff Emeritus
Hello sazzy. Welcome to PF.

Look up the radius of Earth.

Using that, you can find circumference of Earth, which is the distance that a point on the equator travels in one day.

The number of seconds in one day is 24*3600.

If you want to divide some number by 24*3600, you should put (24*3600) in parentheses.

When you computed π/24*3600, that was equivalent to 3600*π/24 . It's just a coincidence that this gave a result that's close to the correct answer.