kingwinner

Yes, Newton (1642-1727) is part of the 17th century

I am writing an essay for a course regarding the history and philosophy of science. The topic is: "During the 17th century, there was intense interaction between science and religion. Using examples, mount an argument that takes a position on this interaction. In other words, with reference to some hisotrical examples, discuss whether you regard this relationship as positive, negative, or a combination of both." What I get from this is that the examples must be from the 17th century. I am only aware of Galileo's trial, the conflict with the church of whether the Earth is stationary or moving. Other than this, I am feeling blank. I can't think of any other figures with examples of interaction between science and religion, can someone kindly remind me of some other examples? Any help is greatly appreciated! Thanks for helping!:D

According to my readings, I would match Galileo with refracting telescope, law of falling bodies, projectile motion, features on the moon, sunspots, Jupiter's Moons (but I can't find any of these on the right side), but I am not aware of his contributions to either centripetal or centrifugal force...did Galileo do any work on it?

This is a practice exam question on a course relating to the history of science that I am trying out in order to prepare for my exam, but I am kind of stuck on this question. I hope somebody can help me out! [Total marks: 7x2=14] I would match: Leibniz with calculus (or Newton? I am not too sure whether each person can be matched to multiple answers...but the total marks for this entire question is 7x2=14 so maybe not...but how can I pick only one of them?) Newton with reflecting telescope Leeuwenhoek with protozoa Halley with comet Galileo? I have no idea which should be match to him... Hooke? Descartes? Can anyone please help me out so that I can gain more confidence before writing the exam? Thanks a lot!:evil:

I am pretty sure that b is false as well... But does anyone know whether c is true or false? Thanks!

I will be writing my final exam tomorrow evening, and I am currently stuck on the following practice problem. It would be very nice if someone could help me out and I will remain eternally grateful for your help! 1) (Multiple Choice) Which of the following statement(s) about Cold Dark Matter (CDM) is (are) incorrect: a) CDM particles travel at a speed much lower than c :phones: neutrinos are a candidate for CDM c) simulation models using CDM produce smaller scale structures than those using Hot Dark Matter d) CDM is likely baryonic e) CDM particles should be more massive than HOT Dark Matter particles Well, I believe that a and e are true, b and d are false, but I am totally unsure about c...is it true or false and why? Does anyone know? Thank you!

In general, which of the gases, N2, CO, and H2, would you expect to behave the most and least ideally? I have no idea how to determine this...can someone help me? Thank you!

1) [The main issue for me here is that I am not sure where the collision will occur. If Odie drops the birdbath right before Garfield touches the it, would the collision occur BELOW 1.5m above the ground? (because the birdbath will be moving AWAY from Garfield? Or will it still occur at exactly 1.5m above the ground as if no dropping of the birdbaths occurs?] 2) [i don't quite understand the situtation here (seems complicated). When Snoppy starts moving, will Charlie Brown also be moving? When will Snoppy come to rest? And is it a momentarily rest or will it stay at rest? At that instant, will Charlie Brown also be at rest?] These problems seem lengthy and complicated to me. Any help is greatly appreciated. :cocktail:

for q1a, I think we should assume the second charge is the charge on the right side(+3.8x10^-6C, but I still don't get the answer. This set of questions is making me crazy...

I know you physictists can calculate these very quickly. :shrug: Could somebody help me with 1 or 2 questions? I still can't get the answers in the book! Thanks!

4) 2 charges of +4.0x10^-6 C and +8.0x10^-6 C are placed 2.0m apart. What is the field strength halfway between them? [i got an answer of 3.6x10^4N/C toward the 4.0x10^-6C charge, but the answer given is 3.6x10^-4N/C toward the larger charge] 5) A point charge of 2.0x10^-6C experiences an electric force of 7.5N to the left. What force would be exerted on a -4.9x10^-5 C charge placed at the same spot? [My answer is 1.8x10^2N , but the answer given is 1.5x10^5N/C ] 6) [i got 3.2x10^5N/C [right], but the answer in the book is 1.8x10^5N/C ]

For the folloing 6 questions, I got completely different (way off) answers from the ones given in the textbook. This is really driving my crazy. I checked my work many times but can't find out what I did wrong. If anyone is interested in physics problems and have the time, I hope you can help me check out whether the answers in the textbook are correct or not, so that I can know if I am correct. I really appreciate for your help! :shrug: I am wondering if I am calculating something seriously wrong so that I am getting way off answers for all these questions. I am afraid and frustrated now that I am losing confidence in this topic. :hihi: 1) A point charge of +3.8x10^-6 C is placed 0.20 m to the right of a charge of -2.0x10^-6 C. What is the force on a third charge of +2.3x10^-6 C if it is placed 1a) 0.10 m to the right of the second charge? [assuming the second charge is the charge on the right side(+3.8x10^-6C), I got an answer of 7.4N , but the answer is 7.9N ] 1b) where would the third charge experience a net force of zero? [i got an answer of 0.53 m to the left of the -2.0x10^-6C charge, but the answer given is 1.2x10^-2 m [right of smaller charge] ] 2) 4 objects, each with a positive charge of 1.0x10^-6 C, are placed at the coreners of a 45-degree rhombus with sides of length 1.0m. Calculate the magnitude of the net force on each charge. [i got 2.2x10^-2 N and 1.9x10^-2 N respectively, but the answers provided are 8.4x10^-3 N and 1.9x10^-2 N respectively.] 3) 3 charges of +1.0x10^-4 C form an equilateral triangle with side length 40cm. What is the magnitude and direction of the electric force on each charge? [i got an answer of 9.7x10^2N[90 degrees from the line joining the other charges], but the answer provided is 8.9x10^2 N[90 degrees away from the line connecting other charges] ]

1) For a positively charged sphere, the electric field lines point outward. For a negatively charged sphere, the electric field lines point inward. Why is it always like that? 2) A charge (3.6x10^-6 C) is 30cm to the left of another charge (-2.7x10^-6 C). Point A is 20cm to the right of the charge with -2.7x10^-6. a) Find the magnitude and direction of the net electric field at point A. :lol: What electric force is exerted on a charge 4.5x10^-6 C placed at point A? c) What electric force is exerted on a charge -4.5x10^-6 C placed at point A? [For part a, I got an answer of 4.8x10^5 N/C For part b, would the electric force have the same direction as the electric field at point A? (i.e. left?) I assumed so, and got an answer of -2.2N The main problem is part c. I don't know how to calculate this. We know that E = Fe/q, where E represents the electric field, Fe is the electric force, and q is the magnitude of the charge at point A. Note that in the equation, q is substitute as a magnitude. So would the negative charge affect anything, will the answer be the same as part b?] 3) A negative charge of 2.4x10^-6 C experiences an electric force of magnitude 3.2 N, acting to the left. a) Calculate the magnitude and direction of the electric field at that point.[The answer is 1.3x10^6N/C . Why is the direction to the right? The electric force has a direction to the left, and since electric force and electric field always have the same direciton, shouldn't the direction of the electric field be to the left also?] ;) Calculate the value of the field at that point if a charge of 4.8x10^-6 C replaces the charge of 2.4x10^-6 C. 4) Consider the setup of two large, equally charge, parallel, flat conducting plates close together, the top plate positive and the bottom plate negative. -The electric field is constant everywhere in the space between the parallel plates. [WHY?] -The magnitude of the electric field at any point between the plates depends and is directly proportional ONLY on the magnitude of the charge on each plate. [Why is it so? I thought that E=Fe/q is the formula for electric field, shouldn't E be inversely proportional to q? (E=electric field, q=charge] -The plate separation has no effect on the electric field. [WHY?] Could anyone explain? I will really appreciate for your help! :wave:

Hi, 1) How do you know that exactly half of the charge is removed? How can this be justified mathematically?

1) Two charged spheres, 10.0 cm apart, attract each other with a force of magnitude 3.0x10^-6 N. What force results if an uncharged, identical sphere is touched to one of the spheres and is then taken far away? 2) What is static electricity? Why and in what way is static electricity "static"? Must electrostatic forces be repulsive? Can electrostatic forces ever be attractive? Thanks for replying!

In this case, the centre has no object (no mass). Both stars are in the circular orbit. Both stars are moving in circular path, so centripetal force should be considered, right? Then, is it true that the force of gravity of star 1 on star 2 provides the centripetal force for star 2, and that the force of gravity of star 2 on star 1 provides the centripetal force for star 1?

Method 2: Fc=Fg mv^2/r = Gmm/D^2 <=====I don't understand this line! Why is r (radius) used for Fc and D (diameter) used for Fg? Shouldn't the radius be used in both cases? Why is the centripetal force on one star equal to the force of gravity supplied by the other star, located in a distance away that equals the diameter? (i.e. Gmm/D^2)? For the regular case, consider a satellite orbitting around earth, in this case, the centripetal force is equal to the force of gravity between the satellite and the earth, but the RADIUS is used in GMm/r^2 instead of the DIAMETER v = square root of (G m r / D^2) v=22371.299m/s v = 2 pi r / T T=2.8x10^7 s Is 7.9x10^7 s definitely the wrong answer? Is it also a conincidence that method 1's answer is exactly half the answer provided?

Can you show me what values you substitute into v = square root of (G m r / D^2) ? I can't get the answer. Besides, using the frame of reference of one of the stars, wouldn't you see the other star as orbitting around you in a circular orbit? (the logic of method 1)

I really need help with this question: 1) A certain "double star" consists of two identical stars, each of mass 3.0x10^30 kg, separated by a distance of 2.0x10^11 m between their centres. They orbit around a common centre of gravity. How long does it take to complete one cycle? (in seconds) [answer: 7.9x10^7 s] Method 1: (my method) This is the method I did. I assumed one of the stars to be stationary, i.e. viewing from the frame of reference on the star, and let the other star orbit aorund it in circular orbit. This becomes like a problem of a satellite orbitting around the earth. Let Fc = centripetal force Fc=Fg ...... T=2pi * square root of (r^3/G m) where m=mass of one of the stars, and r=2x10^11 m =39719490.78 s =4.0x10^7 s Method 2: (my instructor's method) This is what my instructor did. D=Diameter of the circle=2x10^11 m r=raiuds of the circle=1x10^11 m m=mass of one of the stars Fc=Fg ... v = square root of (G m r / D^2) v=22371.299m/s v = 2 pi r / T T=2.8x10^7 s But, both answers are wrong. The correct answer is 7.9x10^7 s. This is a tough tough question for me. Can someone please explain? My method is wrong. I doubt that even my instrctor's method is wrong.

Hi, Why only the change in potential energy? The speed changes too, so does the kinetic energy? Do I have to take the change in kinetic energy into consideration? Also, will the final answer of Q1 be a negative value?

Can somone please explain in greater detail? (especially for Q1) I still don't get how to do.:)

I have a couple more questions on this topic. I hope someone can help me. Thanks a lot! :( 1) A space shuttle ejects a 1.2x10^3 kg booster tank so that the tank is momentarily at rest, relative to Earth, at an altitude of 2.0x10^3 km. Neglect atmospheric effects. How much work is done on the booster tank by the force of gravity in returning it to Earth's surface? [The first thing I can think of is W=Fd(cos theta), but here the force of gravity is not constant so I can't use this formula. How can I find the work done by gravity, then?] 2a) Calculate the escape speed from the surface of the Sun: mass = 1.99x10^30 kg, radius = 6.96x10^8 m. 2b) What speed would an object leaving Earth need to escape from our solar system? [For 2a), I got 6.18x10^5 m/s, but I don't know how to proceed to part :(] 3) Consider a geosynchronous satellite with an orbital period of 24h. What speed must the satellite reach during launch to attain the geosunchronous orbit? (Assume all fuel is burned in a short period. Neglect air resistance.) [On the ground, does the satellite have kinetic energy or is it at rest on the ground?]

2) So basically calculate the change in gravitational potential energy (from ground to altutide of 500km) plus the kinetic energy of the satellite in orbit, am I right? If so, this is basically the work done needed to place a satellite at rest on earth to its orbit, right? And also, the earth is rotating at a very high speed, which gives the object on the ground a very large kinetic energy. Why can we omit this large amount of kinetic energy in the calculations? 3) Can someone explain how to do question 3? At which 2 points will the total energies be equal? Which 2 points should I use? Thank you!

Hi everyone, 1) A black hole has the property that the escape speed is GREATER than the speed of light. (i.e. light can't escape a black hole) The solution did it this way, by substituting c as escape speed: 3x10^8=square root of [2(6.67x10^-11)(5.98x10^24)/r) This means that with a speed of 3x10^8m/s, light CAN escape a black hole, which is not true, right? So is the solution wrong? 2) I was told that Total energy = Eg + Ek, and I can find the total energy at the point where the satellite is in orbit (using the altitude and speed of the satellite). The questions asks for total energy, and I am not sure if this "Total energy" is the required answer... 3) Is it valid to say that the initial velocity will be the same on the earth and the moon and use the kinetic equations to solve this problem? But the weight is different, the applied force is the same, the time interval of upward acceleration (i.e. to jump) is the same, so wouldn't that initial velocity as she leaves the ground be completely different?

Hi, What does d1 represent? And for your step 3, "calculate how much the barge moved", how can I calculate it? I am not too sure... Will the barge be moving forward or backward relative to the water? For the plane's initial velocity of 50m/s, I think it's relative to the BARGE. Which frame of reference should I consider when using the law of conservation of momentum? (is it the barge?)