# Mechatronics Questions and Answers – Acceleration Sensors

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This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Acceleration Sensors”.

1. What will be the value measured by an accelerometer in free fall?
a) Zero
b) Infinite
c) Error
d) 9.81

Explanation: In a free fall the accelerometer will measure value=0. In a stationary state the accelerometer will measure the acceleration due to gravity as 9.81 m/s2 but in a free fall the acceleration of the falling accelerometer is also 9.81 m/s2 in the same direction, therefore the relative acceleration of the accelerometer becomes zero.

2. Which is the name of the accelerometer that is used to measure the gravity of the earth?
a) MPU6050
b) Gravitymeter
c) Gravitometer
d) Gravimeter

Explanation: Gravimeter are the accelerometer that is used to measure the gravity of the earth. The gravity of the earth varies from place to place depending upon the type of plain, plateau etc. This determination of acceleration due to gravity is called gravimetry.

3. What is the exact value of acceleration due to gravity taken in consideration?
a) 10 m/s2
b) 9.80665 m/s2
c) 9 m/s2
d) 0 m/s2

Explanation: The exact standard acceleration due to gravity is taken as 9.80665 m/s2. For general calculations it is assumed to be 10 m/s2. It the acceleration in which the earth pulls all the object present on the surface of earth. This acceleration varies at the poles of the earth.

4. Which element is mostly used in the capacitive accelerometers for sensing?
a) Germanium
b) Silicon
d) Carbon

Explanation: Silicon is mostly used in the capacitive accelerometers for sensing. It is relatively cheap and exhibits far better performance in the low frequency range. They can provide a higher stability and linearity when operated in servo mode.

5. MEMS stands for ________
a) Micro electric mechanical system
b) Micro electro mechanical system
c) Mini electro mechanical system
d) Mini electronic mechanical system

Explanation: MEMS stands for Micro electro mechanical system. Accelerometers, Gyroscopes and pressure sensors are MEMS sensors. It is a technology using which most of the accelerometers and other sensors are designed.

6. Accelerometers can be used for sensing mechanical vibrations.
a) True
b) False

Explanation: Accelerometers can be used for sensing mechanical vibrations. They can detect even very precise vibrations in the machine. Since the vibration is in single plane a two axis accelerometer is best suited for the measurement.

7. Acceleration is a ______ quantity.
a) scalar
b) vector
c) tensor
d) resistive

Explanation: Acceleration is a vector quantity. It is a vector quantity because it depends on both, magnitude of acceleration as well as the direction of acceleration. Had it been only dependent on magnitude, it would be a scalar quantity but it is not so.

8. MPU6050 in an example of which type of sensor?
a) Acceleration sensor
b) Proximity Sensor
c) Ultrasonic sensor
d) Laser sensor

Explanation: MPU6050 is an example of Acceleration sensor. It consists both 3 axis accelerometer and 3 axis gyroscope, which is capable of measuring very precise movements and accelerations.

9. Piezoelectric accelerometers converts ________ energy to ______energy.
a) mechanical, sound
b) mechanical, electrical
c) sound, electrical
d) sound, electrical

Explanation: Piezoelectric accelerometers converts mechanical energy to electrical energy. The word piezoelectric is derived from a Greek word “piezein” which means to press or squeeze. When any mechanical variable such as force or shock is applied on the input, then it produces subsequent electrical signals which is used to measure its magnitude.

10. Which is an example of accelerometer?
a) OptoNCDT ILR 1030
b) OptoNCDT 1420
d) EddyNCDT 3301

Explanation: ADXl 335 is an example of accelerometer. OptoNCDTILR 1030 and OptoNCDT 1420 are laser sensor used for computing distance and objects placed at very high distances. EddyNCDT 3301 is a Eddy currents sensor.

11. A free falling heavy object will have more acceleration than a free falling light object if released from a same height. (Ignore air resistance)
a) True
b) False

Explanation: A free falling heavy object will not have more acceleration than a free falling light object if released from a same height. Both the object will experience same acceleration due to gravity, which is why a free falling light object and heavy object will reach the ground at the same time if released from a same height.

12. Who invented the first accelerometer?
a) Grueblerowen
b) Joseph Henry
c) George Atwood
d) Walther Bothe

Explanation: George Atwood invented the first accelerometer. The first accelerometer was invented in the year 1783 and was originally named as Atwood machine. This machine was used to calculate linear accelerations.

13. What was the original name of first accelerometer?
a) Eskimometer
b) Atwood machine
c) Asimo machine
d) Pepper

Explanation: The original name of first accelerometer was Atwood machine. It was named after its inventor George Atwood. He was an English physicist who invented the first accelerometer in the year 1783.

14. AC (Alternating Current) response accelerometer cannot measure constant or static acceleration.
a) True
b) False

Explanation: AC (Alternating Current) response accelerometer cannot measure constant or static acceleration such as acceleration due to gravity. They are designed to determine dynamic accelerations and events which changes regularly.

15. DC (Direct Current) response accelerometer cannot measure dynamic acceleration.
a) True
b) False 