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Question

Rakesh left home and walked $5$km southwards, then turned right and walked $2$km and again turned right and walked $5$ km and finally again turned left and walked $5$ km. The shortest distance between the final position and home is.

The correct answer is
$7$ km

Understanding Rakesh's Directional Journey

Rakesh's movement can be broken down into distinct steps. We need to track his position relative to his starting point (home) to find the shortest distance.

  • Step 1: Rakesh starts at home and walks 5 km South.
  • Step 2: He turns right from the South direction (which means he faces West) and walks 2 km West.
  • Step 3: He turns right again from the West direction (which means he faces North) and walks 5 km North.
  • Step 4: He turns left from the North direction (which means he faces West) and walks 5 km West.

Calculating Net Displacement

To find the shortest distance, we calculate the net displacement in the North-South and East-West directions. Let's consider South and West as negative directions and North and East as positive directions for simplicity, or track them separately.

North-South Displacement:

  • Movement South: $5$ km
  • Movement North: $5$ km
  • Net North-South Displacement = $5 \text{ km (South)} - 5 \text{ km (North)} = 0 \text{ km}$.

This means Rakesh ends up at the same North-South level as his home.

East-West Displacement:

  • Movement West: $2$ km
  • Movement West: $5$ km
  • Net East-West Displacement = $2 \text{ km (West)} + 5 \text{ km (West)} = 7 \text{ km (West)}$.

So, Rakesh's final position is $7$ km directly West of his home.

Determining the Shortest Distance

The shortest distance between two points is a straight line. Since Rakesh's net North-South displacement is $0$ km, his final position is horizontally aligned with his home. The entire displacement is along the East-West axis.

Therefore, the shortest distance between Rakesh's final position and his home is the net East-West displacement.

Shortest Distance = Net East-West Displacement = $7$ km.

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Important Questions from Direction and Distance (Notes)

  1. A woman leaves her home. She walks 40 m in North-West direction and then 90 m in South-East direction. Then, she moves 30 m in North direction. How far is she now from her initial position ?
  2. N sits to the North of L and West of M. L sits to the East of O. If everyone is facing North, which direction of O, is N?
  3. I starts from Point A and drives 5 km towards the north. He then takes a right turn, drives 2 km, turns right and drives 9 km. He then takes a right turn and drives 7 km. He takes a final right turn, drives 4 km and stops at Point P. How far (shortest distance) and towards which direction should he drive in order to reach Point A again? (All turns are $90^\circ$ turns only unless specified.)

  4. A tourist drives $20 \text{ km}$ towards east, turns right and drives $6 \text{ km}$, then drives $6 \text{ km}$ towards west. He then turns to his left and drives $4 \text{ km}$ and finally turns right and drives $14 \text{ km}$. Where is he from his starting point?

  5. A Couple started to their offices in the morning from their home. While husband drives 3 km South and then 2 km to his right to reach his office, wife goes 2 km towards East for her office. With respect to husband's office, how far and in which direction is the wife's office ?
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