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Grade 12th passMechanics

A certain engine has a stroke of 100mm and the connecting rod is 175mm long between the centres of its bearings. Calculate the distance moved by the piston from TDC position when the connecting rod reaches its maximum angularity relative to the cylinder axis .

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7 Years agoGrade 12th pass
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ApprovedApproved Tutor Answer0 Years ago

To determine the distance moved by the piston from the Top Dead Center (TDC) position when the connecting rod reaches its maximum angularity relative to the cylinder axis, we can use some basic principles of geometry and trigonometry. Let's break this down step by step.

Understanding the Components

In this scenario, we have a few key components:

  • Stroke of the engine: This is the total distance the piston travels from TDC to Bottom Dead Center (BDC), which is 100 mm.
  • Length of the connecting rod: The connecting rod connects the piston to the crankshaft and is 175 mm long.
  • Maximum angularity: This occurs when the connecting rod is at its most inclined position relative to the vertical axis of the cylinder.

Visualizing the Setup

Imagine the engine's piston moving up and down within a cylinder. The connecting rod pivots at the crankshaft and connects to the piston. When the piston is at TDC, the connecting rod is vertical. As the crankshaft rotates, the connecting rod will start to angle away from the vertical, reaching a point of maximum angularity.

Calculating the Distance Moved by the Piston

To find the distance moved by the piston from TDC at maximum angularity, we can use the following approach:

Step 1: Identify the Geometry

At maximum angularity, the connecting rod forms a triangle with the vertical line (the cylinder axis). The length of the connecting rod (175 mm) acts as the hypotenuse of this triangle, while the vertical distance from the crankshaft to the piston represents the adjacent side.

Step 2: Use Trigonometric Relationships

Let’s denote the angle of maximum angularity as θ. The vertical distance (h) from the crankshaft to the piston can be expressed as:

h = L * cos(θ)

where L is the length of the connecting rod (175 mm).

Step 3: Determine the Maximum Angularity

To find the angle θ at maximum angularity, we can use the relationship between the stroke and the length of the connecting rod:

sin(θ) = (Stroke / 2) / L

Substituting the values:

sin(θ) = (100 mm / 2) / 175 mm = 50 mm / 175 mm = 0.2857

Now, we can find θ using the inverse sine function:

θ = arcsin(0.2857) ≈ 16.6 degrees

Step 4: Calculate the Vertical Distance

Now, we can find the vertical distance (h) when the connecting rod is at this angle:

h = 175 mm * cos(16.6 degrees) ≈ 175 mm * 0.9613 ≈ 168.2 mm

Step 5: Determine the Distance from TDC

The distance moved by the piston from TDC is the total stroke minus the vertical distance:

Distance from TDC = Stroke - h = 100 mm - (175 mm - 168.2 mm) = 100 mm - 6.8 mm = 93.2 mm

Final Result

Thus, the distance moved by the piston from the TDC position when the connecting rod reaches its maximum angularity relative to the cylinder axis is approximately 93.2 mm.