Change in velocity, average acceleration

[salaam]

Homework Statement

Earth's orbit around the SUn is nearly circular. THe period is 1 year = 365.25 days. In an elapsed time of 2.70 days, what is Earth's angular displacement? what is the change in Earth's velocity (perpendicular to the average velocity) What is the Earth's average acceleration during 2.7 days? (perpendicular to the average velocity)

Homework Equations

a =v/t
v = s/t

The Attempt at a Solution

I have already completed the first question and got 4.64×10-2 rad and it was right.

but the next two I'm having major problems with. and i am so confused. anyone help!

 

[G01]

You know how fast the Earth's tangential velocity is (or you can get it using the angular displacement and time).

How does the tangential velocity relate to the centripetal acceleration for uniform circular motion?

 

[salaam]

I'm really not sure.. can you elaborate?