### Answers and comments for the review activities and problems in Chapter 1.

#### Guided review:

2. a, b: diameter is 10x, cross sec area is 100x

c: f 2, f

3. 7.5 x 238 = 1785

#### P&RSB:

4. a: 1011

b: ~2.7 x 10 11, of the order of the size of a hydrogen atom.

possible set: neutron, electron, proton, electron, neutrino

15. a: All 100 protons will experience an additional electric repulsion.

b: The nucleons surrounding the added proton (or neutron) - of the order of 8 or so - will experience an additonal nuclear attraction.

As the nucleus gets bigger, the answer to 'a' gets larger but the answer to 'b' does not. (Note that this is not a realistic nucleus. The numbers are for illustration only.)

#### SPP:

A has the greater atomic weight (mass) but K has the greater atomic number (=number of protons), Z. It is Z that determines the place in the periodic table. (Initially it was thought to be the atomic weight.)

9. Mass and weight are proportional to f3.

The energy expenditure is proportional to f2 = (f3)2/3 = M2/3.