# Mechatronics Questions and Answers – Hydraulic Actuator and Output Devices

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Hydraulic Actuator and Output Devices”.

1. Which is not an output device?
a) Seven Segment display
b) Liquid crystal display
c) Lithium battery indicator
d) Lithium battery

Explanation: Lithium battery is not an output device. It can give input to a device. “Seven segment display” is used to display numerical values as well as some English alphabets. Liquid crystal display (LCD) can be used to display anything. Lithium battery indicator is used to display the battery level.

2. Who invented hydraulic press?
a) Norbert wiener
b) Joseph Bramah
c) Charles young
d) Charles wheatstone

Explanation: Joseph Bramah invented hydraulic press. The first patent for hydraulic press was applied and patented by him in the year 1795. Hydraulic press uses hydraulic cylinders to generate compressive force.

3. What is the push provided by a hydraulic fluid used in fluid based actuator, if a steel ball of radius 3cm is immersed in it, Given that the fluid has a density of 1200kg/m3, Take g=10m/s2?
a) 1.695N
b) 3.2N
c) 2.26N
d) 1.356N

Explanation: Given: Density of fluid (ρf) = 1200kg/m3
g=10m/s2
Volume of steel ball (V) = 4/3πr3=4/3π (0.03 m)3
V=1.13*10-4 m3
Push (P) = ρf*g*v
P=1200kg/m3*10m/s*1.13*10-4 m3
P=1.356N

4. What is the push provided by water used in fluid based actuator, if a wooden ball of radius 3cm is immersed in it, Given that the water has a density of 1000kg/m3, wood has a density of 900kg/m3, Take g=10m/s2?
a) 1.695N
b) 3.2N
c) 2.26N
d) 1.13N

Explanation:
Given: Density of water (ρf) = 1000kg/m3
Density of wood (ρw) = 900kg/m3
Since the push or thrust applied by a fluid does not depend on the density of object, so we will not consider the density of wood. Rather we should focus on the density of water.
g=10m/s2
Volume of wooden ball (V) = 4/3πr3=4/3π (0.03 m)3
V=1.13*10-4 m3
Push (P) = ρf*g*v
P=1000kg/m3*10m/s*1.13*10-4 m3
P=1.13N

5. The ON and OFF time of a buzzer can be controlled using PLC control system.
a) True
b) False

Explanation: The ON and OFF time of a buzzer can be controlled using PLC control system. PLC stands for programmable logic controller. It is a digital computer that can control electromechanical machines. The ON and OFF time of a buzzer can be easily controlled through it.

6. Archimedes principle depends on the density of the immersed object.
a) True
b) False

Explanation: Archimedes principle does not depend on the density of the immersed object. It depends on the density of the fluid in which it is being immersed. It also depends on the volume of the object and acceleration due to gravity.

7. What is the push provided by a hydraulic fluid used in fluid based actuator, if a steel ball of radius 3cm is immersed in it, Given that the fluid has a density of 2000kg/m3, Take g=10m/s2?
a) 5N
b) 3.2N
c) 2.26N
d) 4N

Explanation: Given: Density of fluid (ρf)=2000kg/m3
g=10m/s
Volume of steel ball (V) = 4/3πr3=4/3π (0.03 m)3
V=1.13*10-4 m3
Push (P) = ρf*g*v
P=2000kg/m3*10m/s*1.13*10-4 m3
P=2.26N

8. Where will the push provided by a fluid of hydraulic piston will be more? (Consider the pistons are cylindrical and have same height)
a) Wooden piston of density 900 Kg/m3 and radius 6 cm
b) Iron piston of density 7850 Kg/m3 and radius 5 cm
c) Copper piston of density 8940 Kg/m3 and radius 5 cm
d) Glass piston of density 2580 Kg/m3 and radius 3 cm

Explanation: The push provided by a fluid of hydraulic piston will be more in a wooden piston of density 900 Kg/m3 and radius 6 cm. It is so because the push provided by the fluid does not depend on the density of rather it is directly proportional to the volume of the object. Since the wooden piston has maximum radius so the volume is also maximum.

9. How many LED’s (Light Emitting Diodes) are present in 7 segment display?
a) 6
b) 7
c) 8
d) 9

Explanation: 7 LED’s (Light Emitting Diodes) are present in 7 segment display. These 7 LED’s (Light Emitting Diodes) together form up a “8” like structure which can be used to display any number from 0 to 9. Each LED can be controlled individually.

10. Generator is a rotary actuator.
a) True
b) False

Explanation: Generator is not a rotary actuator. An actuator is a machine or mechanical component of a machine that moves and controls the movement of machine. It can be anything that controls the mechanism of a system. A rotary actuator produces rotary motion. But a generator does not provide rotary motion; it provides electricity from rotational motion. So it is not a rotary actuator.

11. What is the push provided by a fluid used in fluid based actuator, if a plastic ball of radius 4cm is immersed in it, Given that the fluid has a density of 1100kg/m3, plastic has a density of 800kg/m3, Take g= 10m/s2?
a) 1.695N
b) 2.9469N
c) 2.26N
d) 1.13N

Explanation:
Given: Density of fluid (ρf) = 1100kg/m3
Density of plastic (ρP) = 800kg/m3
Since the push or thrust applied by a fluid does not depend on the density of object, so we will not consider the density of plastic. Rather we should focus on the density of fluid.
g=10m/s2
Volume of wooden ball (V) = 4/3πr3=4/3π (0.03 m)3
V=2.679*10-4 m3
Push (P) = ρf*g*v
P=1100kg/m3*10m/s*2.679*10-4 m3
P=2.9469N

12. Motor is a rotary actuator.
a) True
b) False

Explanation: Motor is a rotary actuator. An actuator is a machine or mechanical component of a machine that moves and controls the movement of machine. It can be anything that controls the mechanism of a system. A rotary actuator produces rotary motion. Example: motor.

13. How many columns of pixel matrix are present in 16*2 display?
a) 10
b) 12
c) 2
d) 16

Explanation: There are 16 pixel matrixes present in 16*2 display. A 16*2 display is made up of 16 columns and 2 rows of pixel matrix. Each pixel matrix is made up of 5*7 numbers of pixels. In total it has 1120 pixels.

14. How many pixels are there in 16*2 displays?
a) 1000
b) 1200
c) 1120
d) 1100

Explanation: 1120 pixels are present in 16*2 displays. 16*2 display has 32 blocks in which can be used to display any number or character. Each block is made up of 5*7 pixel matrix. So the total number of pixel will be 32*35 = 1120 pixels.

15. What is the push provided by a hydraulic fluid used in fluid based actuator, if a steel ball of radius 3cm is immersed in it, Given that the fluid has a density of 1500kg/m3, Take g=10m/s2?
a) 1.695N
b) 3.2N
c) 2.26N
d) 4N

Explanation: Given: Density of fluid (ρf)=1500kg/m3
g=10m/s2
Volume of steel ball (V) = 4/3πr3=4/3π (0.03 m)3
V=1.13*10-4 m3
Push (P) = ρf*g*v
P=1500kg/m3*10m/s*1.13*10-4 m3
P=1.695N

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