Direction Sense

Direction Sense

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Direction Sense questions ask you to track a person’s facing direction and final position after a string of moves (walks + turns). Cardinal directions are N, S, E, W; intercardinal are NE, NW, SE, SW. Each turn is a fixed angle: left = −90°, right = +90°, U-turn = 180° (cumulative facing angle mod 360°). Distance walked is a vector on a 2D grid where East = +x and North = +y.

• Vector rule: sum east components and north components separately, then apply Pythagoras only for the shortest straight-line displacement.
• Shadow rule: at sunrise → shadow points West; at noon → shadow points South (Northern Hemisphere); at sunset → shadow points East.
• Clock rule: minute hand at 12 = North; each 15-minute step = 90°.

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Facing vs. Movement

A turn changes the facing direction but does not move the person. Only a “walk” statement adds distance. Solve by maintaining a cumulative facing angle modulo 360°, then converting back to the 8-point compass rose (every 45°).

Tracking procedure

For each step: (1) read the instruction, (2) update facing using the turn conversion table, (3) decompose the walk into East (+x) and North (+y) components using the new facing, (4) add to running totals.

Worked example

A person starts facing North, walks 5 km, turns right, walks 3 km, turns left, walks 4 km. Facing sequence: N → E → N. East total = 3 km; North total = 5 + 4 = 9 km. Displacement magnitude = √(3² + 9²) = √90 ≈ 9.49 km.

Shadow and clock analogies

Shadow problems use the sun’s azimuth to infer direction. Clock problems re-label 12 as N and use minute-hand positions (3 = E, 6 = S, 9 = W) — each minute = 6°.

Turn type	Angle change	Effect on facing (if N)
Right	+90°	N → E
Left	−90°	N → W
U-turn	180°	N → S
4 rights	360°	N → N (net)

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Edge cases that trip candidates

A 360° rotation (four consecutive right turns, or two U-turns) leaves facing unchanged but may inflate the apparent move count. Always reset facing before applying the next turn, especially after a long walk that has rotated the person’s local “left/right.” Shadow questions across hemispheres invert the noon rule: in the Southern Hemisphere, noon shadows point North.

Common mistakes

• Confusing left vs. right after the person has rotated (e.g., facing East, “his left” is North, not West).
• Summing total walked distance instead of computing net displacement — examiners love asking for the shortest distance from start to end.
• Treating a “turn back” statement as a 180° turn instead of reversing the previous step’s vector (they cancel, net zero).

Practice prompts

1. Starting facing South, walk 4 km, turn right (now facing W), walk 3 km, turn left (now facing S), walk 5 km, then turn right twice. Find final facing and displacement.
2. At 9:00 a.m. the sun is East and your shadow points West; you turn so the shadow is now on your right. Which direction are you facing?

Exam strategy

MDCAT places 1–2 Direction Sense MCQs inside the ~3% Logical Reasoning block. Budget 60–90 seconds each: sketch a compass, label each turn, and track facing in degrees — never guess left/right in your head.

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