@wings of fire
Q2)A perfectly frictionless DI, is corrected to give zero drift on the ground at 30 degree north. The DI is set to read 100 degree in an a/c stationary on the ground in latitude 45 degree north. The reading after 45 mins will be:
a) 92.33 degree
b)102.50 degree
c)97.78 degree
d) 103.75 degree
@ 30 N -> No Drift
i.e. ER Drift + Real Drift = 0
15Sin30 (Dec(Northern Hemi)) + RD =0
7.5(Dec) + RD = 0
RD = 7.5 Deg/Hr (Inc)
@ 45 N
Total Drift = 15Sin45(Dec) + 7.5 (Inc)
= 10.606(Dec) + 7.5 (Inc)
= 3.1066 Deg/Hr (Dec)
Reading after 45 mins
3.1066 * (45/60) = 2.32995 Deg/45 Mins (Dec)
At 100 degs = 100 - 2.32995 = 97.67005 Degs
Answer (c)