A fully specified small plate
A fictional technical-drawing exercise specifies a plate 120 mm wide and 60 mm high. Two holes have diameter 10 mm. Measured from the left and upper edges, their center coordinates are(20,20)mm and(100,20)mm. The drawing uses the declared first-angle arrangement and a paper scale of 1:2. The task does not specify the material, thickness, tolerances, manufacturing method, permissible stress or current standard to be certified. One student puts both centers 20 mm from the left edge; another dimensions the drawing by measuring the reduced paper distances and writes them as the real feature sizes. A third adds a second conflicting chain of dimensions. The teacher asks for a coherent educational representation that communicates the given geometry and clearly leaves unspecified manufacturing requirements open.
1. Give paper distances for the width, hole diameter and two center coordinates.
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At 1:2 the plate width is 60 mm and the hole diameter 5 mm on paper. Paper center coordinates are(10,10)mm and(50,10)mm from the stated edges. Dimension labels communicate the specified real geometry, not the reduced paper measurements. Thickness, tolerances and material remain unknown. Do not duplicate conflicting locations or pretend the drawing is sufficient to manufacture or certify the plate.
2. Explain how dimensions communicate actual sizes and identify two unknowns.
Read the worked answer
At 1:2 the plate width is 60 mm and the hole diameter 5 mm on paper. Paper center coordinates are(10,10)mm and(50,10)mm from the stated edges. Dimension labels communicate the specified real geometry, not the reduced paper measurements. Thickness, tolerances and material remain unknown. Do not duplicate conflicting locations or pretend the drawing is sufficient to manufacture or certify the plate.