### 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: 10^{11}

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 f^{3}.

The energy expenditure is proportional to f^{2} = (f^{3})^{2/3} = M^{2/3}.