physics questions read and revise

1. 101 exp.some examples of centripetal force
2. 160 diff.types of equilibrium
3. 171Why do helicopters have two propellers?
4. What will happen if your cycle wheels have no spokes?
5. why is the ladder most apt to slip when you are high up on it than when you just begin to climb?
6. 207 why  a man can jump higher on the moon than on the earth?
7. 209 diff.between inertial/gravitational mass.
8. 214 State Kepler's law of planetary motion
9. What are asteroids?
10. What are constellations?
11. 
    
12.