4-9. During what stroke  in the operating cycle  of  a  4-stroke  Otto-cycle engine  is  the  greatest  force exerted  on  the  piston  head? 1.    Intake 2.   Compression 3.   Power 4.   Exhaust 4-10. Which  of  the  following  events occurs  during  the  exhaust  stroke  in a  4-stroke  Otto-cycle  engine? 1. Fuel-,air-mixture  is  ignited 2. Temperature  and  pressure  of mixture  increases 3. A partial vacuum is created 4. Burnt gasses are cleared from 4–13. Which,    if any, of the following components  determine(s)  the position  of  the  valves? 1. The pistons 2. The  camshaft 3. The  crankshaft 4. None of the above 4-14. The ignition system is timed so that the spark occurs before the piston  reaches   TDC on which of the following  strokes? 1. Exhaust 2. Intake 3. Power 4. Compression the cylinder 4-15. Which  of  the  following  engine 4-11. The  basic  difference  between  the 2-stroke–cycle  and  the 4-stroke-cycle  diesel  engine  is  in the 1. number of pistons 2. piston  arrangement 3. number  of  piston  strokes  during 4–16. a  cycle   of events 4. distance  is  piston  travels during a stroke 4-12. How  many  crankshaft  revolutions  are required for each power stroke in a (a) 4-cycle engine and (b) 2-cycle engine? 1. (a) Two (b) one 2.  (a) Four (b) two 3. (a) One (b) two 4. (a) Two (b)) four classification  methods  is  the  most common? 1. Type of fuel used 2. Cylinder   arrangement 3. Valve  arrangement 4. Type of cooling used Combustion  takes  place  as  a  result of ignition by what in a (a) diesel engine  and  (b)  gasoline  engine? 1. (a) Expansion of compressed gases (b) a Spark 2. (a) Heat of compression (b) a spark 3. (a) A spark (b) heat of compression 4. (a) A spark (b) expansion of compressed gases 34