GATE 2021 ME (ME2) – Question 52
A 76.2 mm gauge block is used under one end of a 254 mm sine bar with roll diameter of 25.4 mm. The height of gauge blocks required at the other end of the sine bar to measure an angle of 30° is _____ mm (round off to two decimal places).
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Correct answer: 202.18 to 204.22
Explanation
Sine-bar angle satisfies $\sin\theta=(h_2-h_1)/L$, where L is roller-centre spacing. Therefore height difference is 254 sin 30°=127 mm.
The raised end needs 76.2+127=**203.20 mm**. Equal roll radii cancel, so roll diameter does not enter the height difference.