JNTU
JNTU B.Tech I ENGINEERING GRAPHICS Previous Question Paper (October/November - 2020 - R16)
Answer any three questions. All questions carry equal marks.
Main
A circle of 50 mm diameter rolls on horizontal line for a half revolution and then on the vertical line for another half revolution. Draw the curve traced out by a point P on the circumference of the circle.
Answer
The curve traced by a point on the circumference of a circle rolling without slipping is a cycloid. For this problem, the path is divided into two stages:
- Draw a horizontal line and a vertical line meeting at a corner.
- Draw the circle of diameter 50 mm (radius r = 25 mm) at the starting position on the horizontal line. Divide the circle into 12 equal parts and mark points 1, 2, ..., 12.
- Calculate the distance for half a revolution: πr = 3.14 × 25 = 78.5 mm. Divide this distance into 6 equal parts.
- Project the points from the circle to the corresponding horizontal positions to locate the path of point P for the first half revolution.
- For the second half revolution, the circle rolls vertically. The center of the circle moves along a path parallel to the vertical line. Repeat the division process for the vertical movement, ensuring the point P continues its rotation relative to the new center positions.
- Connect the resulting points with a smooth curve to complete the cycloid path.
The actual length of 500 meters is represented by a line of 15 cm on drawing. Construct a vernier scale to read up to 600 meters. Mark on scale a length of 549 Meters.
Answer
To construct the vernier scale, follow these steps:
- Calculate the Representative Fraction (RF): RF = Length of drawing / Actual length = 15 cm / 500 m = 15 cm / 50000 cm = 3 / 10000.
- Calculate the Length of Scale (LOS): LOS = RF × Maximum length = (3 / 10000) × 600 m = 18 cm.
- Draw a line 18 cm long and divide it into 6 equal parts, each representing 100 m. Divide the first part into 10 subdivisions, each representing 10 m.
- Construct the vernier scale above the main scale. Divide a length of 11 subdivisions of the main scale (110 m) into 10 equal parts to create the vernier divisions. Each vernier division represents 11 m.
- To mark 549 m: Take 500 m on the main scale, 40 m on the main scale subdivisions, and 9 m on the vernier scale (since 549 - 540 = 9). The distance from the 4th subdivision mark on the main scale to the 9th mark on the vernier scale represents 549 m.
The major axis of an ellipse is 150 mm long and the minor axis is 100 mm long. Find the foci and draw the ellipse by arcs of circles method. Draw a tangent and normal to the ellipse at a point on it 25 mm above the major axis.
Answer
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Construct a diagonal scale of R.F.=1/6250 to read up to 1 kilometer and to read meters on it. Show a length of 653 meters on it.
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The top view of a 75 mm long line CD measures 50 mm. C is 50 mm in front of V.P. and 15 mm below the H.P., D is 15 mm in front of V.P. and is above H.P. Draw the front view of CD and find its inclinations with H.P. and V.P. and also find its traces.
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A plate having shape of an Isosceles triangle has base 50 mm long and altitude 70 mm. It is so placed in the front view it is seen as an equilateral triangle of 50 mm sides and one side is inclined at 45° to XY. Draw its top view.
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The end A of a line AB is in the H.P. and 25 mm behind the V.P. The end B is in the V.P. and 50 mm above H.P. The distance between the end projectors is 75 mm. Draw the projections of AB and determine its true length, traces and inclinations with the two planes.
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A semi circular plate of 80 mm diameter has its straight edge in the V.P. and inclined at 45° to the H.P. The surface of the plate makes an angle of 30° with the V.P. Draw its projections.
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A cone of the diameter of the base 40 mm and axis 75 mm, apex in H.P. and axis vertical and 40 mm in front of V.P. Draw its projections.
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One of the body diagonals of a cube of 45 mm edge is parallel to the H.P. and inclined at an angle of 45° to the V.P. Draw the top view and front view of the cube.
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Draw Front view, Top view and side view for the following figure. All dimensions are in mm.
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