Accelerometer sensor

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Quick Questions

Shade in the A or B circle for each question.

1. Which data does an accelerometer capture?

A Acceleration (change in speed or direction) and tilt

B The amount of light falling on it

2. Which device feature uses an accelerometer to turn the screen when you rotate the phone?

A Phone screen rotation

B Phone screen brightness

3. A step counter detects each step by sensing...

A The temperature of the person's skin

B The movement of the body as each step is taken

4. In a car, what does an accelerometer help an airbag system to detect?

A A sudden impact or sharp slowing down

B The level of fuel in the tank

5. True or false: an accelerometer can measure the tilt of a device.

A False

B True

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1accelerometer		AAn accelerometer does not measure temperature. It measures acceleration, movement and tilt. A temperature sensor measures heat.
2accelerometer reading changes when phone is turned sideways		BA sensor that measures acceleration (change in speed or direction) and the tilt of a device
3A step counter uses an accelerometer to detect the repeated movement of walking		CAn accelerometer measures acceleration, which is a change in speed or direction, so a constant speed gives no acceleration.
4A car airbag system uses an accelerometer to detect a sudden impact		DIF acceleration < -50 THEN inflate airbag
5A phone uses an accelerometer to measure the temperature of its battery		EThe sensor detects the tilt of the device, so the screen can rotate
6An accelerometer only measures when a device is moving at a constant speed		FIF accelerometer detects a jolt THEN steps ← steps + 1

Definitions

accelerometer

Fill in the Blanks

Complete each line of code by filling in the missing parts.

tilt ← READ(_____________) IF tilt > 45 THEN ENDIF

__ tilt > 45 THEN OUTPUT "Landscape" ENDIF

IF impact _ 8 THEN OUTPUT "Inflate airbag" ENDIF

IF movement = TRUE THEN steps ← steps _ 1 ENDIF

IF impact > 8 THEN OUTPUT "Inflate airbag" _____

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A tilt <- accelerometer.read()

B IF tilt = sideways THEN

C rotate screen to portrait

D ENDIF

Question 2

A steps <- 0

B IF jolt detected THEN

C steps <- steps - 1

D OUTPUT steps

Question 3

A impact <- accelerometer.read()

B IF impact < 50 THEN

C inflate airbag

D ENDIF

Question 4

A tilt <- microphone.read()

B IF tilt > 45 THEN

C rotate screen

D ENDIF

Question 5

A steps <- 0

B WHILE app is open

C IF jolt detected THEN

D steps <- steps * 2

E ENDIF

F ENDWHILE

Answer Key

Accelerometer sensor

Section A: Quick Questions

A — Acceleration (change in speed or direction) and tilt

A — Phone screen rotation

B — The movement of the body as each step is taken

A — A sudden impact or sharp slowing down

B — True

Section B: Match the Pairs

accelerometer → A sensor that measures acceleration (change in speed or direction) and the tilt of a device

accelerometer reading changes when phone is turned sideways → The sensor detects the tilt of the device, so the screen can rotate

A step counter uses an accelerometer to detect the repeated movement of walking → IF accelerometer detects a jolt THEN steps ← steps + 1

A car airbag system uses an accelerometer to detect a sudden impact → IF acceleration < -50 THEN inflate airbag

A phone uses an accelerometer to measure the temperature of its battery → An accelerometer does not measure temperature. It measures acceleration, movement and tilt. A temperature sensor measures heat.

An accelerometer only measures when a device is moving at a constant speed → An accelerometer measures acceleration, which is a change in speed or direction, so a constant speed gives no acceleration.

Section C: Definitions

accelerometer — A sensor that measures acceleration (change in speed or direction) and tilt. Used for phone screen rotation, step counters and car airbag impact detection.

Section D: Fill in the Blanks

tilt ← READ(accelerometer)
IF tilt > 45 THEN
ENDIF

IF tilt > 45 THEN
  OUTPUT "Landscape"
ENDIF

IF impact > 8 THEN
  OUTPUT "Inflate airbag"
ENDIF

IF movement = TRUE THEN
  steps ← steps + 1
ENDIF

IF impact > 8 THEN
  OUTPUT "Inflate airbag"
ENDIF

Section E: Spot the Error

C — When the accelerometer detects the phone tilted sideways, the screen should rotate to landscape, not stay in portrait.

C — Each jolt from a footstep, detected by the accelerometer, should add 1 to the step count. It should be steps <- steps + 1.

B — The airbag must inflate only when the accelerometer reads a very large, sudden change in speed. The condition should be impact > 50.

A — A microphone captures sound, not tilt. Tilt is measured by an accelerometer, so it should be tilt <- accelerometer.read().

D — A step counter adds 1 for each movement the accelerometer detects. Multiplying by 2 would give a wrong count. It should be steps <- steps + 1.