ME 454: Mechatronics (Penn State) Exam 1
Questions and Answers
1. The Greenswork Zero-turn radius lawnmower features a 60-volt battery - Is this safe?: Probably
not safe - the voltage is slightly above that of electrocution.
2. The Greenswork Zero-turn radius lawnmower features a 60-volt battery. What assumptions are
being made by the engineers?: 1) The users will not touch the leads of the battery.
2) If the user touches the leads, the skin is not very conductive (not sweaty, for example).
3) The user will not drive the mower into water.
4) The voltage is close enough to the limit that, if a user is handling the battery, it is probably
low enough in voltage to be safe to handle.
3. The Greenswork Zero-turn radius lawnmower features a 60-volt battery. How is the battery safer by
using lithium-ion technology?: It won't easily poison the user or environment if handled,
especially if the battery corrodes.
4. How many 12-volt car batteries can be used in series before a possible electrocution?: 4
(Must be less than 50 V, so 12 V * 4 = 48 V < 50 V)
5. What bad thing can happen if you put your finger in your mouth after burning it?: Poisoning.
6. What bad thing can happen if you simply blow on your finger after burning it?: Burn gets worse.
7. What bad thing can happen if you hold your finger in your hand and cut off any circulation that can
spread the burn, after burning it?: Burn gets worse.
8. "set up" or "loop": Something that sets the initial value of the output on Pin
2.: Setup
9. "set up" or "loop": A routine that only needs to run 30 times, then never run again.: Setup
10."set up" or "loop": A routine that continually blinks an LED on or off, forever.: Loop
11."set up" or "loop": A routine that buzzes only when a user flips a switch, and the switch can be
flipped over and over, forever, to turn the buzzer on/off.: Loop
12."set up" or "loop": A routine that buzzes only the first time the Arduino turns on.: Setup
13."set up" or "loop": A routine that prints continuous updates on the Ar- duino's status when
running.: Loop
14.The following code is from the DigitalInputPullup example, from the built-in examples on the
Arduino's "Examples" folder. It runs, but includes several coding practices that are not very good.
Note: the header comments are not included, but this isn't the problem we are examining - the
problems are in the code, not comments.
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15
, ME 454: Mechatronics (Penn State) Exam 1
Questions and Answers
In the code below, what are two poor practices that should be avoided?: 1) Hard-coding the
number for the pins for input and output.
2) Writing an if statement such that a variable appears before the constant in an equality or
inequality operation.
15.Other than cutting through the circuit board with a Dremel, why is it likely that this circuit board
could be damaged in the images below?: The board is likely to be damaged by static build-up due
to the way the hand is on top of the board.
16.Say you were checking a clock to see if a 1-hour class is over.
What would be the MAXIMUM time you should wait before checking the clock, according to Nyquist
sampling theory?
(Minutes): Maximum = 1/2 times the measurement So, 1/2*60
= 30 minutes
17.Say you were checking a clock to see if a 1-hour class is over.
What would be a SUGGESTED time to wait before checking the clock?
(Minutes): X = 60 minutes/10 X = 6
minutes
Suggested: Want to measure system at roughly 10 times the fastest frequency
18.Say you were recording music, assuming that the human ears can hear to 20 kHz.
What would be the MINIMUM frequency to sample sound, according to Nyquist sampling theory?:
Minimum = 2 times faster than what we want
20 kHz * 2 = 40 kHz
19.Say you were recording music, assuming that human ears can hear to 20 kHz.
What would be a SUGGESTED frequency to sample sound?: Suggested: Want to measure system
at roughly 10 times the fastest frequency
X = 20*10 = 200 kHz
20. Say you were measuring the motion of a pendulum swinging back and forth at 1 cycle per
second.
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15
Questions and Answers
1. The Greenswork Zero-turn radius lawnmower features a 60-volt battery - Is this safe?: Probably
not safe - the voltage is slightly above that of electrocution.
2. The Greenswork Zero-turn radius lawnmower features a 60-volt battery. What assumptions are
being made by the engineers?: 1) The users will not touch the leads of the battery.
2) If the user touches the leads, the skin is not very conductive (not sweaty, for example).
3) The user will not drive the mower into water.
4) The voltage is close enough to the limit that, if a user is handling the battery, it is probably
low enough in voltage to be safe to handle.
3. The Greenswork Zero-turn radius lawnmower features a 60-volt battery. How is the battery safer by
using lithium-ion technology?: It won't easily poison the user or environment if handled,
especially if the battery corrodes.
4. How many 12-volt car batteries can be used in series before a possible electrocution?: 4
(Must be less than 50 V, so 12 V * 4 = 48 V < 50 V)
5. What bad thing can happen if you put your finger in your mouth after burning it?: Poisoning.
6. What bad thing can happen if you simply blow on your finger after burning it?: Burn gets worse.
7. What bad thing can happen if you hold your finger in your hand and cut off any circulation that can
spread the burn, after burning it?: Burn gets worse.
8. "set up" or "loop": Something that sets the initial value of the output on Pin
2.: Setup
9. "set up" or "loop": A routine that only needs to run 30 times, then never run again.: Setup
10."set up" or "loop": A routine that continually blinks an LED on or off, forever.: Loop
11."set up" or "loop": A routine that buzzes only when a user flips a switch, and the switch can be
flipped over and over, forever, to turn the buzzer on/off.: Loop
12."set up" or "loop": A routine that buzzes only the first time the Arduino turns on.: Setup
13."set up" or "loop": A routine that prints continuous updates on the Ar- duino's status when
running.: Loop
14.The following code is from the DigitalInputPullup example, from the built-in examples on the
Arduino's "Examples" folder. It runs, but includes several coding practices that are not very good.
Note: the header comments are not included, but this isn't the problem we are examining - the
problems are in the code, not comments.
1/
15
, ME 454: Mechatronics (Penn State) Exam 1
Questions and Answers
In the code below, what are two poor practices that should be avoided?: 1) Hard-coding the
number for the pins for input and output.
2) Writing an if statement such that a variable appears before the constant in an equality or
inequality operation.
15.Other than cutting through the circuit board with a Dremel, why is it likely that this circuit board
could be damaged in the images below?: The board is likely to be damaged by static build-up due
to the way the hand is on top of the board.
16.Say you were checking a clock to see if a 1-hour class is over.
What would be the MAXIMUM time you should wait before checking the clock, according to Nyquist
sampling theory?
(Minutes): Maximum = 1/2 times the measurement So, 1/2*60
= 30 minutes
17.Say you were checking a clock to see if a 1-hour class is over.
What would be a SUGGESTED time to wait before checking the clock?
(Minutes): X = 60 minutes/10 X = 6
minutes
Suggested: Want to measure system at roughly 10 times the fastest frequency
18.Say you were recording music, assuming that the human ears can hear to 20 kHz.
What would be the MINIMUM frequency to sample sound, according to Nyquist sampling theory?:
Minimum = 2 times faster than what we want
20 kHz * 2 = 40 kHz
19.Say you were recording music, assuming that human ears can hear to 20 kHz.
What would be a SUGGESTED frequency to sample sound?: Suggested: Want to measure system
at roughly 10 times the fastest frequency
X = 20*10 = 200 kHz
20. Say you were measuring the motion of a pendulum swinging back and forth at 1 cycle per
second.
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15
