- 376

- 0

**Rotational Kinematics, Challenge!!!!!**

**1. Homework Statement**

A satellite follows an elliptical orbit. The only force on the satellite is the gravity atraction from the planet. The satellites speed at point A is 8000m/s, and it is 6000km away, Point B is 24000km east of the planet, and Point C is component vector 9000ikm+12000jkm away, if the you take the planet as the origin.

a. Is there any torque acting on the satellite?

b. satellite speed at Point B

c, satellite speed at Point C

**2. Homework Equations**

We have just started rotational kinematics, and have not yet done space physics like newtons constant of gravity and that stuff. So just Lf=Li, conservation of momentum.

**3. The Attempt at a Solution**

a. i supect there is no torque because there is no external force acting on the satellite, as the gravity act as the moment arm.

b and c. i used La=Lb=Lc, therefore RaVa=RbRb=RcVc,

therefore giving Vb=(RaVa)/Rb and Vc=(RaVa)/Rc, and that Rc=sqrt(9000^2+12000^2)=15000, so my answers i get are 2000m/s at point B and 3200m/s at Point C, but the answers in the book say 2000m/s and 4000m/s..... so can someone please tell me where i have gone wrong??? TY