🧷 Authentic Classroom Explanation by IAS Monk

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📌 The Question:

Consider the following actions:

1. Detection of car crash/collision which results in the deployment of airbags almost instantaneously
2. Detection of accidental free fall of a laptop towards the ground which results in the immediate turning off of the hard drive
3. Detection of the tilt of the smartphone which results in the rotation of display between portrait and landscape mode

In how many of the above actions is the function of accelerometer required?

(a) Only one
(b) Only two
(c) All three
(d) None

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✅ Answer: (c) All three

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🧑‍🏫 Classroom Explanation:

An accelerometer is a sensor that measures linear acceleration, changes in motion, vibration, and the effect of gravity.

Let us examine each action:

• Action 1 – Airbag deployment:
During a collision, the vehicle experiences sudden deceleration. Accelerometers detect this rapid change in acceleration and instantly trigger airbag deployment. Hence, required.

• Action 2 – Laptop free fall protection:
Modern laptops use accelerometers to detect sudden free fall. When detected, the hard drive is immediately powered down or the read/write head is parked to prevent data loss. Hence, required.

• Action 3 – Smartphone screen rotation:
Smartphones use accelerometers to sense orientation relative to gravity, allowing automatic switching between portrait and landscape modes. Hence, required.

Since accelerometers are essential in all three cases, the correct answer is (c).

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🔍 Curiosity Raiser:

📱 Ever wondered how your phone knows which way is “up” even when GPS is off?

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📚 Enrichment Notes (UPSC Edge):

• Accelerometers convert mechanical motion into electrical signals
• Commonly combined with gyroscopes in IMUs (Inertial Measurement Units)
• Used in:
  • Vehicle safety systems
  • Smartphones and wearables
  • Aerospace and missile guidance
  • Earthquake detection and structural monitoring

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🧘 IAS Monk Whisper:

🌀 When motion speaks, accelerometers listen.