My Math Forum Degrees and Radians

 Algebra Pre-Algebra and Basic Algebra Math Forum

 October 20th, 2007, 11:54 AM #1 Newbie   Joined: Oct 2007 Posts: 19 Thanks: 0 Degrees and Radians The earth rotates on its axis once every 24 hours. a)How long does it take earth to rotate through an angle of 4pi/3? b)how long does it take earth to rotate through an angle of 120 degree?
 October 20th, 2007, 12:32 PM #2 Senior Member   Joined: Dec 2006 Posts: 1,111 Thanks: 0 There are 360 degrees and 2*pi radians in a complete revolution. Does that help? Just find the ratio between the angle being traveled by the Earth in the problem and the number of degrees/radians in a full revolution, and then multiply that by the amount of time it takes the Earth to rotate around its axis.
 October 21st, 2007, 03:47 PM #4 Global Moderator   Joined: May 2007 Posts: 6,663 Thanks: 649 Slight nitpicking. The earth takes slightly less (I think about 4 min.) than 24 hours to rotate 360 deg. The extra time is needed to complete an earth day because the earth has moved 1/365th of its distance in orbit around the sun.
 October 21st, 2007, 05:32 PM #5 Senior Member   Joined: Dec 2006 Posts: 1,111 Thanks: 0 I can't see how motion around the sun influences the length of the day. If we define a point that the Earth starts from and ends from in regards to spinning motion, moving around the Sun shouldn't influence that (I think).
October 21st, 2007, 07:25 PM   #6
Global Moderator

Joined: Dec 2006

Posts: 20,104
Thanks: 1907

Quote:
 Originally Posted by Infinity I can't see how motion around the sun influences the length of the day.
If you had permanent day, the rotation rate would be one rotation per year, wouldn't it?

October 21st, 2007, 08:08 PM   #7
Senior Member

Joined: Dec 2006

Posts: 1,111
Thanks: 0

Quote:
 I can't see how motion around the sun influences the length of the day.
OK, so you are defining the day as how much time we get sunlight. I am defining it as how long it takes the Earth to spin once (360 degrees) on its axis.

Quote:
 If you had permanent day, the rotation rate would be one rotation per year, wouldn't it?
Yes, similar to the moon going around the Earth.

October 22nd, 2007, 02:48 PM   #8
Global Moderator

Joined: May 2007

Posts: 6,663
Thanks: 649

Quote:
 Originally Posted by Infinity I can't see how motion around the sun influences the length of the day. If we define a point that the Earth starts from and ends from in regards to spinning motion, moving around the Sun shouldn't influence that (I think).
A day is defined in terms of how the earth is facing the sun, that is from noon to noon, where noon is defined as the time that the sun is directly overhead (at the appropriate latitude). Since the earth has moved in its orbit, it has to rotate more than 360 deg. to get there.

,
,

,

,

,

,

,

,

,

,

,

,

,

,

# through how many radians does the earth turn in 1 hour

Click on a term to search for related topics.
 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post not3bad Algebra 4 October 3rd, 2013 11:43 PM milly2012 Algebra 1 April 29th, 2012 09:26 AM hemidol Algebra 1 April 8th, 2012 08:19 PM Phazon Calculus 10 June 6th, 2011 06:08 PM 9nuza0902 Algebra 2 October 29th, 2008 04:56 PM

 Contact - Home - Forums - Cryptocurrency Forum - Top