Match the engines in the following list with their drawbacks. Place your answer in the blank space given. i. gunpowder engine ii. Savery engine iii. Newcomen engine iv. Watt engine a._ The boiler could not withstand the steam pressure needed to lift water beyond 6 m. b._ The engine had no mechanism to move the piston back to complete a cycle. c._ The continual reheating needed after each cooling of the engine cylinder required a tremendous amount of thermal energy. d._ This engine was large and massive and less efficient than thought possible.

The correct options are;

a. ii. Savery engine The boiler could not withstand the steam pressure needed to lift water beyond 6 m.

b. i.Gunpowder engine The engine had no mechanism to move the piston back to complete a cycle

c. iii. Newcomen engine The continual reheating needed after each cooling of the engine cylinder required tremendous amount of thermal energy

d. iv. Watt engine This engine was large and massive and less efficient than thought possible

Explanation:

a. The evaporation of the water due to the effect of creating a vacuum limits the Savery's engine pressure differential to about 20 (which is approximately 6 meters) to 25 feet of suction

b. In The gunpowder engine after providing power to a mass, there is less provision to move the piston to a position to lift another mass

c. Energy from burning of fuel was needed to heat the steam cylinder (the steam and the steel wall) repeatedly which consumed a considerable energy in the Newcomen engine

d. In the Watt steam engine the increased efficiency attainable was 17.4% while the actual efficiency was about 11% with the addition of a separate condenser unit.