1. An ice skater is in a spin with his arms extended so his hands are 0.711 m from the spin axis. a) If the period of the spin is 0.527 s per rotation, what is the centripetal acceleration of his hands? b) If he tucks his arms close to his body so his hands are 0.320 m from the spin axis, the spin increases so the period decreases to 0.153 s per rotation. Now what is the acceleration of his hands?

2. A 4.67 g penny is placed at the outer edge of a vinyl record turntable with a radius of 15 cm.If the coefficient of friction is 0.830 at what minimum speed does the penny fly off?

3. An indoor bicycle racing track is banked at an angle of 70 with a radius of 40.0 m. If the bicyclist and equipment have a combined mass of 88 kg, what centripetal force is experienced?

4. You are in a space capsule above an unknown planet. When you are 1000 km above the surface you are going at 3123 m/s in orbit. To increase the orbit to 2000 km above the surface you change your velocity to 2818 m/s.What is the a) radius of the planet and b) mass of the planet?

Write down the key words or phrases for the following problems (5&6). Do not fully solve the problem. Do not solve the equation for the missing variable.

5. At an amusement park there is a ride in which cylindrically shaped chambers spin around a central axis. People sit in seats facing the axis, their backs against the outer wall. At one instant the outer wall moves at a speed of 3.2 m/s, and an 83-kg person feels a 560-N force pressing against his back. What is the radius of the chamber?

6. An 830-kg race car can drive around an unbanked turn at a maximum speed of 58 m/s without slipping. The turn has a radius of curvature of 160 m. Air flowing over the car's wing exerts a downward-pointing force (called the downforce) of 11 000 N on the car. What is the coefficient of static friction between the track and the car's tires?