Examkin

Question

Difficulty: MediumThe Earth as a Planet and Earth Movements

A radio station in Town A (10∘E10^\circ\text{E}) broadcasts a live news program at 1:45 p.m. local standard time. A researcher at Station B hears the broadcast live when the local standard time at Station B is 8:05 a.m. on the same day. What is the longitudinal position of Station B?

  1. 75∘W75^\circ\text{W}Answer
  2. B
    95∘E95^\circ\text{E}
  3. C
    85∘W85^\circ\text{W}
  4. D
    65∘W65^\circ\text{W}

Answer

Station B is located at 75∘W75^\circ\text{W}.
Station B experiences a local time that is 5 hours and 40 minutes behind Town A. Because Earth rotates 15∘15^\circ per hour (1∘1^\circ every 4 minutes), this time lag equals an angular distance of 85∘85^\circ to the west. Moving 85∘85^\circ west from 10∘E10^\circ\text{E} crosses the Prime Meridian (0∘0^\circ) after 10∘10^\circ, placing Station B at 75∘W75^\circ\text{W}.

Step-by-Step Solution

1
Calculate the time difference between Town A and Station B.
1:45 p.m. (13:45) minus 8:05 a.m. (08:05) = 5 hours and 40 minutes.
Determining the absolute local time difference between the two locations establishes the angular separation.
2
Convert the total time difference into degrees of longitude.
5 hours = 5×15∘=75∘5 \times 15^\circ = 75^\circ; 40 minutes = 40/4=10∘40 / 4 = 10^\circ. Total angular distance = 75∘+10∘=85∘75^\circ + 10^\circ = 85^\circ.
Earth rotates 15∘15^\circ per hour, which equals 1∘1^\circ every 4 minutes.
3
Determine direction and final meridian.
Since Station B's time is earlier (8:05 a.m. vs 1:45 p.m.), it lies west of Town A (10∘E10^\circ\text{E}). 85∘ West of 10∘E=85∘−10∘=75∘W85^\circ\text{ West of } 10^\circ\text{E} = 85^\circ - 10^\circ = 75^\circ\text{W}.
Traveling west moves backward in local time relative to eastern longitudes.

Key Concept

Longitude and Time Difference Calculations
Rate this question

Topics

The Earth as a Planet and Earth Movements

More questions from this topic