Examkin

Question

Difficulty: MediumProperties of Fluids

An outdoor hydraulic lift operates noticeably slower and requires more effort from the pump on a freezing winter morning compared to a hot summer afternoon. Assuming the mechanical components are functioning normally, which of the following fluid properties best explains this sluggish performance?

  1. The viscosity of the hydraulic fluid increases in cold temperatures, creating greater internal resistance to flow.Answer
  2. B
    The liquid hydraulic fluid becomes highly compressible in freezing conditions, causing the pump's energy to compress the fluid rather than move the cylinder.
  3. C
    The fluid expands as it cools down, significantly lowering its specific gravity and reducing its ability to push the cylinder.
  4. D
    The colder fluid provides less buoyant force against the internal piston, making the external load effectively heavier to lift.

Answer

The viscosity of the hydraulic fluid increases in cold temperatures, creating greater internal resistance to flow.
Viscosity measures a fluid's internal resistance to flow. In virtually all lubricating and hydraulic liquids, viscosity increases as the temperature drops, causing the fluid to become thicker. This increased thickness creates drag inside the hydraulic lines and valves, resulting in slower mechanical operation.

Step-by-Step Solution

1
Analyze the mechanical symptom described in the scenario.
The hydraulic lift is operating slowly (sluggishly) in cold temperatures.
Identifying the symptom helps isolate which physical property of the fluid is changing with the temperature drop.
2
Evaluate how temperature affects the physical properties of liquids.
As temperature decreases, the internal friction of a liquid increases.
Understanding the inverse relationship between temperature and liquid viscosity is a core concept in mechanical fluid maintenance.
3
Connect the changing fluid property to the mechanical outcome.
Higher internal friction (higher viscosity) means the fluid resists flowing through hoses and valves, slowing down the machine's operation.
This confirms that increased viscosity is the direct cause of the sluggish mechanical performance.

Key Concept

Viscosity and Temperature Relationship
Estimated Time:45s
Rate this question

Topics

Properties of Fluids

More questions from this topic