Fill in the blank with the most appropriate word from the options given below:
The arm of the excavator at the building site lifts heavy loads by means of ______, as oil pushed through narrow pipes moves the arm up and down.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Hydraulics
Complete sentence: The arm of the excavator at the building site lifts heavy loads by means of hydraulics, as oil pushed through narrow pipes moves the arm up and down.
| Word | Meaning | Example |
|---|---|---|
| (1) Hydrology | the study of water on and under the earth, such as rivers, rain and ground water | A hydrology survey showed that the ground water in the district was falling every year. |
| (2) Pneumatics | the use of air under pressure to make machines work | The bus doors open with a hiss because they work on pneumatics. |
| (3) Hydraulics (answer) | the use of a liquid, such as oil or water, pushed under pressure to move machines, and the study of this | The brakes of most cars work through hydraulics, with brake oil carrying the push of the foot to the wheels. |
| (4) Hydroponics | growing plants in water mixed with nutrients, without soil | Sameer grows lettuce on his terrace using hydroponics, in pipes of flowing water. |