Uniform Circular Motion

[hytuoc]

Would someone plz show me how to do these problems below. Thanks.
1) An Earth satellite moves in a circular orbit 640km above Earth's surface w/ a period of 98.0min. What are (a) the speed and (b) the magnitude of the centripetal acceleration of the satellite?

2) a boy whirls a stone in a horizontal circle of radius 1.5m and at height 2.0 above level ground. the string breaks, and the stone flies off horizontally and strikes the ground after traveling a horizontal distance of 10m. What is the magnitude of the centripetal acceleration of the stone while in circular motion?

[Leong]

#1
Use v=\frac{2\pi r}{T} with
v= the speed of the satellite
r= the radius of the circular orbit of the satellite
T= the period taken by the satellite to make one revolution

Use a=\frac{v^2}{r} with
a= the magnitude of the centripedal acceleration of the satellite
v= the speed of the satellite
r= the radius of the circular orbit of the satellite

#2
Use a=\frac{v^2}{r} with
a= the magnitude of the centripedal acceleration of the stone
v= the speed of the stone when the string breaks
r= the radius of circular path of the stone
Manipulate the formula to obtain v which is the horizontal initial velocity of the stone when the string breaks. The rest is about 2D projectile motion.