**PreQuiz 5.1 .:. Go Up**

**Gravity and Circular Motion**

**Show your work, and circle your answers and use sig figs
to receive full credit.**

1. What is the period of a merry-go-round with a radius of 1.75 m if the centripetal acceleration at this point is 7.2 m/s/s? (3.1 s)

2. What is the velocity of a 1350 kg car going around a 213 m radius corner if the frictional force is 9830 N? (39.4 m/s)

Questions 1 and 2 are simple centripetal acceleration, 2 is incorporates the idea of centripetal force

3. Tycho twirls a 2.7 kg hammer at 6.2 m/s around a 5.6 m radius circle. What force in what direction must he exert on the hammer at the top and at the bottom? (8.0 N up, and 45 N up)

Questions 3 is a vertical circle question

4. At what distance from the center of a 4.59 x 10^{24}
kg planet is the gravitational force on a 15.0 kg object equal to 60.0 N? (8.75x10^{6} m)

Question 4 is a simple application of the force of gravity

5. Your 12,500 kg spaceship is orbiting 1.16x10^{7}
m from the center of a planet every 17,500 s. What is the mass of the planet? (3.02x10^{24} kg)

Question 5 is an orbit question: