# angular speed, tangetial speed.

• Nov 23rd 2007, 03:30 PM
rcmango
angular speed, tangetial speed.
The earth orbits the sun once a year (3.16 x 10^7 s) in a nearly circular orbit radius 1.50 x 10^11 m. With respect to the sun, determine the following.

(a) the angular speed of the earth

(b) the tangential speed of the earth
m/s

(c) the magnitude and direction of the earth's centripetal acceleration magnitude m/s^2

i don't understand why a kinematic equation does not work for this.
• Nov 23rd 2007, 11:52 PM
rcmango
anyone around to grab this one please?
• Nov 24th 2007, 01:39 AM
CaptainBlack
Quote:

Originally Posted by rcmango
The earth orbits the sun once a year (3.16 x 10^7 s) in a nearly circular orbit radius 1.50 x 10^11 m. With respect to the sun, determine the following.

(a) the angular speed of the earth

$\dot{\theta}=2\pi/\tau = 2\pi/[3.16\times 10^7]$ rad/s

Quote:

(b) the tangential speed of the earth
m/s
$v_{tang}=r \dot{\theta}$

Quote:

(c) the magnitude and direction of the earth's centripetal acceleration magnitude m/s^2
Direction is radialy inwards and its magnitude is:

$
a_{centripedal}=v_{tang} \dot{\theta}
$

RonL
• Nov 24th 2007, 02:08 AM
rcmango
i'm not sure how the answer is reached by the above calc, but 1.99e-07 is correct. for the first one. i got 4.186E-11 ?
• Nov 24th 2007, 10:31 AM
CaptainBlack
Quote:

Originally Posted by rcmango
i'm not sure how the answer is reached by the above calc, but 1.99e-07 is correct. for the first one. i got 4.186E-11 ?

There was a type (now corrected) but you should be on the look out for these.

RonL