Compression, Differentials and Converters: teacher key

Gas and Electric Cars, grade 9 edition, written for 9th grade. Spark or squeeze, one speed or many: see the choices that shape how a car makes power and how it passes that power to the wheels.

Read the book. Print this page for the key.

Questions and answers

1. How does a diesel engine make fuel ignite?
   • By compressing air and spraying fuel into the hot air (answer)
   • With a spark plug
   • With a hand crank
2. What lets the wheels spin at different speeds while both are still powered?
   • The thermal system
   • The differential (answer)
   • The DC/DC converter
3. What replaced the hand crank on gasoline cars in 1912?
   • A starter motor (answer)
   • A multi-speed motor
   • A drive shaft
4. Why do spark plugs not appear in diesel engines?
   • Diesel needs no air
   • Diesel is too cold
   • Diesel is ignited by compression (answer)
5. What does the DC/DC converter do?
   • Changes high-voltage DC power to lower-voltage DC power for accessories (answer)
   • Turns the wheels
   • Lights the fuel

Words

• compression: squeezing
• diesel: fuel-igniting engine
• differential: wheel speed gear
• crankshaft: spinning engine part
• converter: power changer