- #1

jrd007

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1) Suppose a space shuttle is in orbit 400km from the Earth's surface, and circles the Earth once every 90 minutes. Find the centripital acceleration of the space shuttle's orbit. Express your answer in terms of g, the gravitational acc. or the Earth's surface.

*Okay, so my approach:*

First change 400km into m = 40,000m & 90min = 5400s

So since a=v^2/r, I will find velocity first. So I used Vel=2(pie, 3.14)(r)/t

(2 x 3.14 x 40,000m)/5400s = 465.4 m/s

Then I took a=v^2/r. So ... a=465.4^2/40,000m and got .541 m/s^2

Then convert into g's, .541/9.8 = .06 gBut the correct answer is

First change 400km into m = 40,000m & 90min = 5400s

So since a=v^2/r, I will find velocity first. So I used Vel=2(pie, 3.14)(r)/t

(2 x 3.14 x 40,000m)/5400s = 465.4 m/s

Then I took a=v^2/r. So ... a=465.4^2/40,000m and got .541 m/s^2

Then convert into g's, .541/9.8 = .06 g

**0.9 g's**What am I doing wrong!? :(

2) What is the max speed w/ which a 1050-kg car can round a turn with a radius of 77m on a flat road if the coefficent of static friction b/t tires and road is 0.80?

*What I tried to do was find my acceleration so I could get my velocity but I have no idea how to do that? Since the velocity is not given... Can anyone help me?*Correct answer:

**25 m/s**