Two special cases of horizontal circular motion:
1) a ball rolling round the inside of a hemispherical bowl in a circular path
2) a conical pendulum suspended from two identical strings anchored at points above and below the mass.
Note two small errors:
1) in the hemispherical bowl explanation I typed the word 'bow'
2) In the 2-string pendulum explanation I describe step 5 as 'solving by substitution' and then proceed to solve the simultaneous equations by elimination
