Help Needed: Last-Minute Practice Questions for a Competition

[dawn_pingpong]

I'm getting a rather annoyed I have typed all these stuff twice already, and both times the page just tells me to sign in (although I'm signed in already).

Homework Statement

1) a carnival ferris wheel has a 25m radius and completes five turns about its horizontal axis every minute. What is the acceleration of a passenger at his lowest point?

2)

3)

4)

5)

Homework Equations

6)

7) three polarising plates are stated. The first and third are crossed, the one between has its polarising direction at 45 degrees to the polarising direction of the other two. what fraction of the intensity of an originally unpolarised beam is transmitted by the stack?
8)

9)

The Attempt at a Solution

1) I use formula a=4(pi*r*f)^2 so I got 60++. However the answer is 4.1m/s^2
2) I know use the formula R=ρl/A, but I don't know how to do if there are 2 materials of different resistivity.
3) apparently we will need to use boyle's law, But I don't know how to use it.
4) I have no idea what the question is about...
5) Can use E=mc^2, to find that it is 8.5kg/s and thus 7.3 x 10^5 kg/day. But then the ans is 1.8*10^5
6) Fleming's Left hand rule does not work. or is it about cross product?
7) I thought that it should be 25%, however the answer is 12.5%. Why?
8) I used P=VI, and V=IR, to find that the resistance of the wire is 120Ω. So when it is halved, apply the 2 equations again, and found that the total power is 480W. However, the ans is 800W.
9) For this question, i considered 2 forces: F(float)=ρVg and gravity. However, I was unable to obtain the answer. Let x= the mass of Hg needs to be added. then 9.81*1/7870+9.81=9.81*(x/13550)+9.81x. solving for x, x=1.000058, which is not the ans obviously.

Any inputs will be appreciated:) These are not homework questions as per say, just some practice question for a comp I'm going for next week. Last minute cramping! My foundation is rather weak, so it will be good if anyone can provide some partial solution (or intuition) to some of the questions! Help greatly appreciated!

 

[anathema]

I understand your frustration with having to type all of your work twice. It can be very frustrating to encounter technical difficulties while trying to complete an assignment. I would like to offer some possible solutions to the problems you have encountered.

1) For the first question, it seems like you have the correct formula, but you may have made a calculation error. Can you show your work so I can check for any errors? The correct answer should indeed be 4.1m/s^2.

2) I am not sure which specific formula you are referring to for this question. Can you please provide more information or the full question so I can assist you better?

3) Boyle's law states that the product of pressure and volume is constant for a fixed amount of gas at a constant temperature. In this case, you can use the formula P1V1 = P2V2, where P1 and V1 are the initial pressure and volume, and P2 and V2 are the final pressure and volume. Can you show your attempt at the solution so I can help you further?

4) Without knowing the specific question, I am unable to provide any assistance. Please provide more information or the full question so I can assist you better.

5) The formula E=mc^2 is used to calculate the energy equivalent of mass, not the mass itself. For this question, you can use the formula P = m/t, where P is power, m is mass, and t is time. Can you show your work so I can help you identify any errors?

6) Fleming's left hand rule is used to determine the direction of the force on a current-carrying wire in a magnetic field. Without knowing the specific question, I am unable to provide any assistance. Please provide more information or the full question so I can assist you better.

7) To calculate the fraction of intensity transmitted by the stack of polarising plates, you can use the formula I/I0 = cos^2(theta), where I is the intensity of the transmitted light, I0 is the intensity of the incident light, and theta is the angle between the polarising direction of the first and third plates. Can you show your work so I can help you identify any errors?

8) It seems like you have the correct approach for this question, but you may have made a mistake in your calculations. Can you show your work so I can