Homework Ch 4, 5, and 9

Chapter 4:

p. 130: #3, 8, and 9

3) 3 kg on Ceres.

8)128 planetesimals. (127.56 to be more exact), probably more in order to get the correct density... not sure about this one.

9) 2,500 comets per year over 500 million years.

Chapter 5:

p. 158m: #2,4

2) 1/5 of the weight. (30kg on moon vs. 150kg on earth).