## 9677 #21

mhazelm
Posts: 193
Joined: Sat Sep 06, 2008 3:33 pm

### 9677 #21

Hi everyone,

this problem confused me a bit. I know I can find the centripetal acceleration and set it equal to the gravitational force, but when they ask about "orbiting" speed it made me think of escape velocity and such... the v I get is okay for orbiting? Here's the problem:

The curvature of Mars is such that its surface drops a vertical distance of 2 m for every 3600 m tangent to the surface. In addition, the gravitational acceleration near its surface is 0.4 times that near the surface of Earth. What is the speed a golf ball would need to orbit Mars near the surface, ignoring the effects of air resistance?

anyone able to offer more insight into this one?

Helio
Posts: 809
Joined: Thu Mar 15, 2007 7:11 pm

### Re: 9677 #21

it is problem 22

it is a geometry problem. the radius changes and so you use centripetal forces... it is way to hard for the current exams.

tonyhongxp
Posts: 12
Joined: Thu Oct 16, 2008 9:36 pm

### Re: 9677 #21

orbiting around the surface...
supposedly the surface is rounded... and it's a circle...

grae313
Posts: 2297
Joined: Tue May 29, 2007 8:46 pm

### Re: 9677 #21

have you checked http://grephysics.net ?

mhazelm wrote:Hi everyone,

this problem confused me a bit. I know I can find the centripetal acceleration and set it equal to the gravitational force, but when they ask about "orbiting" speed it made me think of escape velocity and such... the v I get is okay for orbiting? Here's the problem:

The curvature of Mars is such that its surface drops a vertical distance of 2 m for every 3600 m tangent to the surface. In addition, the gravitational acceleration near its surface is 0.4 times that near the surface of Earth. What is the speed a golf ball would need to orbit Mars near the surface, ignoring the effects of air resistance?

anyone able to offer more insight into this one?