Some questions from the navy oar mechanical comprehension

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    Mechanical Navy
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Discussion Overview

The discussion revolves around various mechanical comprehension questions from a Navy exam, focusing on concepts related to forces, tension, electrical circuits, heat exchange, and mechanical systems. Participants express confusion over specific questions and seek clarification on the underlying principles involved.

Discussion Character

  • Homework-related
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant questions the weight of a woman in a dragster during acceleration, suggesting it decreases, while another argues that she presses back into the seat due to acceleration.
  • In a circuit question, one participant believes current is greater at point A, while another asserts that there is no circuit present.
  • Regarding the movement of a negatively charged object between two other charges, one participant states it will be attracted to the positive charge, while another expresses uncertainty about the direction.
  • Participants discuss heat exchange rates, with one suggesting that a larger temperature difference leads to faster heat exchange, while another references Newton's law of cooling to support this view.
  • In a bicycle question, one participant speculates about the effects of wheel size on pedaling difficulty, while another suggests that the configuration does not matter significantly.
  • There is confusion over the distances traveled by points on two connected wheels, with one participant claiming they travel the same distance, while another clarifies that the chain's movement dictates the distances.
  • In a question about tension in weights hanging from a ceiling, one participant believes the heavier weight exerts more pull, while another emphasizes that the force is determined by the weight itself, regardless of distance from the ceiling.
  • Participants express confusion over a pulley question and the amount of rope required to be pulled, with one suggesting that additional context, such as a picture, would be helpful.

Areas of Agreement / Disagreement

Participants do not reach consensus on several questions, with multiple competing views presented, particularly regarding the effects of acceleration on weight, the behavior of charges, and the principles governing tension in hanging weights.

Contextual Notes

Some questions lack clarity due to missing context or assumptions, such as the specific configurations of mechanical systems or the precise wording of questions. Participants also express uncertainty about the implications of distance in tension-related questions.

Who May Find This Useful

Individuals preparing for mechanical comprehension tests, particularly those related to military or technical examinations, may find the discussion relevant.

homeylova223
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I am looking at the following exam the mechanical comprehension part and I am having trouble with some of the questions. Here is the link
https://drive.google.com/drive/folders/1ITIf6mx4RmDoL96IYoH-eY6-jQPh7CUv.

I am having trouble with the following
3. A woman sits in a dragster the beginning of a race. As the light turns green she steps on the accelerator. At the moment the dragster begins to accelerate what is her weight pushing into the seat relative to while the car was stationary?
a.less than while stationary
b. the same a while stationary
c. more than while stationary

Not sure since force=mass(acceleration). I would say her weight would decrease.

11. Where is the current greater in this circuit?
+A<------(--X)----->--B
a. greater at A than B
b.greater b than a
c. the same at A and B

I think electrons flow from positive to negative so greater than A is my answer.

12. X which has a negative charge is positioned between positive charge A and negative charge B. What direction will x move
A.a
B.b
C. remain where it is

15. the rate of heat exchange is faster
a.between a ice cube and 100 celsius glass of water
b.an icecube and 40 celsius water
c.none of the above

I thought since the colder glass is already cold they would exchange heat quicker because the temp difference is less. But heat exchange is faster when temperature difference is large.

20. This one has a picture in the exam. It basically ask what is hard pedaling a bicycle with large front wheel and small back wheel or a small front wheel small back wheel up a hill?

22. This questions ask two wheels are connected by a chain. Point a is a point on the edge of the large wheel and point B is the point on the edge of a smaller wheel. If larger wheel makes one revolution does point a travel a large distance than point b?

I would say they travel the same distance because point a travels a larger distance but point b travels a smaller circumferance but makes more revolutions.

25.question about anchor I do not get it. I thought point A has more tension because it also has anchor pulling on it.

28. Question about tension. Two weight are hanging by a rope from a ceeling one is only 5 pounds but has a greater distance from the ceeling. One is 10 pounds but has shorter distance from the ceiling. Which one exerts more pull on the ceeling?

I thought it was the heavier one but I am wrong.

33. question about a pulley. I put B since I thought force of gravity would also help.

34 Which systems requires more rope to be pulled. Do not really get it.
 
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It is full astb practice test pdf
 
homeylova223 said:
I am looking at the following exam the mechanical comprehension part and I am having trouble with some of the questions. Here is the link
https://drive.google.com/drive/folders/1ITIf6mx4RmDoL96IYoH-eY6-jQPh7CUv.

I am having trouble with the following
3. A woman sits in a dragster the beginning of a race. As the light turns green she steps on the accelerator. At the moment the dragster begins to accelerate what is her weight pushing into the seat relative to while the car was stationary?
a.less than while stationary
b. the same a while stationary
c. more than while stationary

Not sure since force=mass(acceleration). I would say her weight would decrease.
Haven't you ever ridden in a car? When you accelerate from a stop, the car pushes you forward so you press back into the seat.

11. Where is the current greater in this circuit?
+A<------(--X)----->--B
a. greater at A than B
b.greater b than a
c. the same at A and B

I think electrons flow from positive to negative so greater than A is my answer.
There is NO circuit!

12. X which has a negative charge is positioned between positive charge A and negative charge B. What direction will x move
A.a
B.b
C. remain where it is
A negative charge is repelled by another negative charge and is attracted by a positive charge.

15. the rate of heat exchange is faster
a.between a ice cube and 100 celsius glass of water
b.an icecube and 40 celsius water
c.none of the above

I thought since the colder glass is already cold they would exchange heat quicker because the temp difference is less. But heat exchange is faster when temperature difference is large.
"Newton's law of cooling": Heat flows from a higher temperature to a lower at a rate proportional to the difference in temperature. That is it flows faster when the temperature is larger not when it is less.

20. This one has a picture in the exam. It basically ask what is hard pedaling a bicycle with large front wheel and small back wheel or a small front wheel small back wheel up a hill?
Imagine one very large wheel and one very small wheel. You are essentially riding a uni-cycle and it doesn't matter where the small wheel is. There will be no difference.

22. This questions ask two wheels are connected by a chain. Point a is a point on the edge of the large wheel and point B is the point on the edge of a smaller wheel. If larger wheel makes one revolution does point a travel a large distance than point b?
I would say they travel the same distance because point a travels a larger distance but point b travels a smaller circumferance but makes more revolutions.
I assume the chain runs over the circumferences of the two wheels. The distances the two circumferences move is equal to the distance the chain moves. There is no difference.

25.question about anchor I do not get it. I thought point A has more tension because it also has anchor pulling on it.
I have no idea what you are talking about!

[quote\28. Question about tension. Two weight are hanging by a rope from a ceeling one is only 5 pounds but has a greater distance from the ceeling. One is 10 pounds but has shorter distance from the ceiling. Which one exerts more pull on the ceeling?

I thought it was the heavier one but I am wrong.
Why do you say that is wrong? The distance a weight hangs says nothing about the force on the ceiling- that is entirely due to the weight. (Unless there is some kind of torque arm you didn't tell us about.)

33. question about a pulley. I put B since I thought force of gravity would also help.

34 Which systems requires more rope to be pulled. Do not really get it.
What?? I suspect a picture would be useful here.
 
The picture is the link but let me see I can upload the pdf.
 
picture1.jpg
 
picture2.jpg

33. Confuses me I thought it would be A because gravity helps.

34. not sure
 
homeylova223 said:
28. Question about tension. Two weight are hanging by a rope from a ceeling one is only 5 pounds but has a greater distance from the ceeling. One is 10 pounds but has shorter distance from the ceiling. Which one exerts more pull on the ceeling?

I thought it was the heavier one but I am wrong.
Here in the original post you correctly decide that the 10 pound weight will exert more pull on the ceiling than a 5 pound weight regardless of rope length.

But in post #5 above, we see a screen shot which says that the actual question is about which weight will exert less pull. Clearly that will be the 5 pound weight.
 
Sorry I wrote it wrong. I will only post the images now.
 
homeylova223 said:
Sorry I wrote it wrong. I will only post the images now.
Enough already. Proper form is one question per post, done in the homework forum with typewritten work shown, using the template provided.
 
  • #10
homeylova223 said:
Sorry I wrote it wrong.

As @jbriggs444 has pointed out:

jbriggs444 said:
Proper form is one question per post, done in the homework forum with typewritten work shown, using the template provided.

Please start a new thread in the appropriate homework forum and fill out the homework template. This thread is closed.
 

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