Question map
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?
Explanation
The correct answer is Option 3 (All three) because an accelerometer is a micro-electromechanical system (MEMS) sensor designed to measure non-gravitational acceleration and changes in orientation.
The specific applications are explained below:
- Action 1: In car safety systems, the accelerometer detects the sudden, extreme negative acceleration (deceleration) caused by a collision. This rapid change in velocity triggers the ECU to deploy airbags instantly.
- Action 2: Modern laptops use accelerometers to detect a "zero-g" or free-fall state. Upon sensing this, the system parks the hard drive's read/write head to prevent data loss or physical damage upon impact.
- Action 3: In smartphones, the accelerometer measures the direction of gravity relative to the device. This data allows the operating system to determine the device's orientation (tilt) and switch the display between portrait and landscape modes.
Since all three scenarios rely on measuring acceleration or orientation changes, the accelerometer is essential for every function listed.
PROVENANCE & STUDY PATTERN
Guest previewThis is a classic 'Applied Science' question targeting everyday technology. It bypasses standard textbooks entirely, rewarding candidates who possess 'technological curiosity'—asking 'how does this work?' about the devices in their pockets rather than just rote-learning physics definitions.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Statement 1: Is an accelerometer used in vehicles to detect a car crash/collision and trigger near-instantaneous airbag deployment?
- Statement 2: Is an accelerometer used in laptops to detect accidental free fall and immediately turn off or park the hard drive?
- Statement 3: Is an accelerometer used in smartphones to detect device tilt and automatically rotate the display between portrait and landscape?
- Directly names accelerometers as sensors that detect deceleration relevant to crashes.
- Explicitly states accelerometers trigger airbag deployment in severe frontal impacts.
- Describes sensors detecting a serious crash and sending the signal that ignites the inflator.
- Provides the timing for airbag inflation (under 0.05 seconds), supporting 'near-instantaneous' deployment once sensors trigger it.
- Defines what an accelerometer measures (linear acceleration), indicating it can detect the rapid deceleration characteristic of a crash.
- Supports the plausibility that accelerometers can serve as the 'sensors' referenced in airbag systems.
States that vehicles are fitted with instruments (speedometer, odometer) that measure motion-related quantities.
A student could infer that since vehicles already carry motion sensors, other sensors (e.g., accelerometers) could also be installed to measure rapid changes in motion associated with a crash.
Asks whether an object applying force must be in contact, teaching that forces change motion — the underlying concept of acceleration.
Using the basic physics link between force and change in motion, a student could reason that measuring sudden changes in motion (acceleration) can indicate a collision.
Discusses whether a force can change speed or direction, reinforcing that acceleration describes changes in motion.
A student can combine this with knowledge that abrupt large accelerations/decelerations are signatures of crashes and thus detectable by sensors.
Describes an anemometer that converts rotational motion into a measured speed via counting rotations — an example of a sensor converting physical motion into an electrical/counted signal.
By analogy, a student could reason that devices exist which convert mechanical motion (rapid deceleration) into electronic signals that could trigger systems like airbags.
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