Gravitation Question 38

Question: What should be the velocity of earth due to rotation about its own axis so that the weight at equator become 3/5 of initial value. Radius of earth on equator is 6400 km [AMU 1999]

Options:

A) [7.4×104,rad/sec]

B) [6.7×104,rad/sec]

C) [7.8×104,rad/sec]

D) [8.7×104,rad/sec]

Show Answer

Answer:

Correct Answer: C

Solution:

Weight of the body at equator = [35]

of initial weight [g=35g]

(because mass remains constant) [g=gω2Rcos2λ]

Þ [35g=gω2Rcos2(0)]

Þ [ω2=2g5R]

Þ [ω=2g5R=2×105×6400×103] = [7.8×104radsec]



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