Question

Elijah, an astrophysicist, was observing the celestial bodies in the night sky. He made three observations and noted down the time of the observations. His observations were made at 7:00pm, 9:30pm and 11:20pm. He needs to know by what angle the Earth had rotated by the time he made his 2nd and 3rd observations relative to his 1st observation. Can you help him out?

• A. 37.5 degrees and 27.5 degrees
• B. 27.5 degrees and 37.5 degrees
• C. 37.5 degrees and 65 degrees
• D. 27.5 degrees and 65 degrees

Answer 1

The correct option is C 37.5 degrees and 65 degrees

The Earth rotates by 360 degrees in 24 hours or by 1 degree in 4 minutes. Therefore by the time Elijah made his 2nd observation, the Earth had rotated by 150/4= 37.5 degrees and his 3rd observation, the Earth had rotated by 260/4= 65 degrees.