Question

Difficulty: HardDirection and Distance Test

Match each multi-step movement track in List I with its corresponding net displacement vector (shortest distance and direction from the starting point) in List II.

  • Track I: Starting facing North, a field surveyor turns 4545^\circ right and walks 122 m12\sqrt{2}\text{ m}, then turns 135135^\circ right and walks 20 m20\text{ m}, and finally turns 9090^\circ left and walks 3 m3\text{ m}.17 m17\text{ m}, South-East
  • Track II: A drone flies 16 m16\text{ m} due East, turns 9090^\circ left and flies 18 m18\text{ m}, turns 135135^\circ left and flies 102 m10\sqrt{2}\text{ m}, turns 135135^\circ right and flies 4 m4\text{ m}, and finally turns 9090^\circ left and flies 6 m6\text{ m}.12 m12\text{ m}, North
  • Track III: At sunrise, a traveler walks 15 m15\text{ m} directly towards his shadow, turns 9090^\circ right and walks 9 m9\text{ m}, and then turns 135135^\circ right and walks 152 m15\sqrt{2}\text{ m}.6 m6\text{ m}, South
  • Track IV: A security officer walks 5 m5\text{ m} due South, turns 4545^\circ left and walks 122 m12\sqrt{2}\text{ m}, turns 135135^\circ left and walks 22 m22\text{ m}, and finally turns 9090^\circ left and walks 7 m7\text{ m}.52 m5\sqrt{2}\text{ m}, North-East

Answer

Track I matches with 17 m, South-East; Track II matches with 12 m, North; Track III matches with 6 m, South; Track IV matches with 5√2 m, North-East.
Each movement track is correctly paired with its net displacement vector by projecting sequential movements onto a standard Cartesian coordinate grid: Track I resolves to (15, -8) which is 17 m South-East; Track II resolves to (0, 12) which is 12 m North; Track III resolves to (0, -6) which is 6 m South; Track IV resolves to (5, 5) which is 5√2 m North-East.

Step-by-Step Solution

1
Decompose Track I using Cartesian coordinates.
Path vector components: (+12,+12)+(0,20)+(+3,0)=(+15,8)(+12, +12) + (0, -20) + (+3, 0) = (+15, -8). Distance = 152+(8)2=17 m\sqrt{15^2 + (-8)^2} = 17\text{ m}, direction is South-East.
Resolving each angular turn into xx and yy displacements determines net position accurately.
2
Decompose Track II using Cartesian coordinates.
Path vector components: (+16,0)+(0,+18)+(10,10)+(0,+4)+(6,0)=(0,+12)(+16, 0) + (0, +18) + (-10, -10) + (0, +4) + (-6, 0) = (0, +12). Distance = 12 m12\text{ m}, direction is North.
Sequential tracking of direction changes ensures exact final location.
3
Determine initial cardinal direction for Track III using solar shadow properties, then resolve coordinates.
Sunrise shadow points West. Path vectors: (15,0)+(0,+9)+(+15,15)=(0,6)(-15, 0) + (0, +9) + (+15, -15) = (0, -6). Distance = 6 m6\text{ m}, direction is South.
The morning shadow implicitly fixes the initial movement along the negative x-axis.
4
Decompose Track IV using Cartesian coordinates.
Path vector components: (0,5)+(+12,12)+(0,+22)+(7,0)=(+5,+5)(0, -5) + (+12, -12) + (0, +22) + (-7, 0) = (+5, +5). Distance = 52+52=52 m\sqrt{5^2 + 5^2} = 5\sqrt{2}\text{ m}, direction is North-East.
Sub-cardinal movement vectors resolved via 2\sqrt{2} multiples simplify to exact integer Cartesian shifts.

Key Concept

Direction and Distance Test - Vector Decomposition and Relative Displacement
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