Knock, Torque and Timing: teacher key

Gas and Electric Cars, grade 11 edition, written for 11th grade. Timing decides whether a gas engine runs smoothly or knocks. See how fuel, gears and motors are tuned, and what is lost along the way.

Read the book. Print this page for the key.

Questions and answers

1. What happens if fuel ignites too early because of compression?
   • The battery charges
   • The wheels lock
   • The engine knocks (answer)
2. What does a torque converter let the engine do while the car is stopped?
   • Idle (answer)
   • Charge
   • Knock
3. As of November 2026, how much energy does an EV electric drive system lose?
   • 64% to 75%
   • 15% to 20% (answer)
   • 1% to 2%
4. Why does wheel-motor layout remove driveshafts and differentials?
   • The motors are attached directly to the wheel (answer)
   • The motors are far from the wheels
   • There are no wheels
5. What does higher-octane gasoline help fuel do?
   • Burn without air
   • Charge the battery
   • Ignite on time from the spark plug (answer)

Words

• octane: fuel rating
• torque: twisting force
• armature: turning part
• gearbox: gear housing
• hybrid: engine-motor car
• differential: wheel speed gear