Some questions from the navy oar mechanical comprehension

[homeylova223]

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 celcius glass of water
b.an icecube and 40 celcius 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.

 

[homeylova223]

It is full astb practice test pdf

 

[HallsofIvy]

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 celcius glass of water
b.an icecube and 40 celcius 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.

 

[homeylova223]

The picture is the link but let me see I can upload the pdf.

 

[homeylova223]

 

[homeylova223]

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

34. not sure

 

[jbriggs444]

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.

 

[homeylova223]

Sorry I wrote it wrong. I will only post the images now.

 

[jbriggs444]

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.

 

[PeterDonis]

Sorry I wrote it wrong.

As @jbriggs444 has pointed out:

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.