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1. Wave-Particle Duality (QED)

I have been reading Richard Feynmans Quantum Electrodyamics and quite early in the first chapter he asserts that Photons are particles. His reasoning that as you decrease the intensity of light incident on a photomultiplier the clicks which the multiplier make become less frequent but equally...
2. Maximum velocity of a mass undergoing SHM

Question; A 1 g mass is suspended by a spring and executes simple harmonic motion when released. At time t=0 the displacement is 40 cm and acceleration is -3.6 cm/s^2. What is the spring constant k? What is the maximum velocity of this mass? At what time would the modulus of the maximum velocity...
3. Finding the spring constant of a mass in SHM

Question: This is question from A.P French vibrations and waves, problem 3-1 for anyone whom may have it An object of mass 1 g is hung from a spring and set in oscillatory motion. At t=0 the displacement is 43.785 cm and the acceleration is -1.7514 cm/sec^2. What is the spring constant? My...
4. Calculating the temperature of the sun using wavelength of iron atoms

I had this question given in my class A spectral line from iron (mass 55.934 amu) atoms in the sun is measured as 637.4 nm. It's width is measured to be 0.053 nm. Calculate the temperature of the sun? Now I done this using a formulae I was given but it yielded an answer no where near 5778K...
5. Two point charges connected by a massless rope

Question: Two positive charges q(a) and q(b) and masses m(a) and m(b) are at rest, held together by a massless string of length d. Now the string is cut, and the particles fly off in opposite directions. How fast are each going when they are far apart. My attempt: From this the first thing I...
6. Question about phase transitions and PV, VT diagrams

Question: A) Explain what happens when a gas is kept in a cylinder under constant pressure while being cooled. Assume that constant pressure is less than critical pressure. Draw PT and VT diagrams for this? B) Describe and explain what is seen when a strong transparent container of constant...
7. Electrostatic potential of a circular ring

I'm a little stumped with this problem, I have posted a photograph below as there is a diagram to compliment the question Expressions which I used where V(r)= k q/r Where q= σ da Where da is an element of area And k= 1/4πε I messed around with these expressions for a while but it...
8. Electrostatic fields- What defines an electrostatic field?

I have a question about electrostatic fields! I was given these two equations E= k [xy xˆ + 2yz yˆ + 3xz zˆ] E= k[y^2 xˆ+ (2xy+ z^2)+ 2yzzˆ] And asked to determine if either could be an electrostatic field, I'm not asking how to solve this problem but I'm not sure what defines an...
9. Using Taylor expansion to find the limits of a function

I had been assigned this problem, I worked out the expansions (for practice) so they could have errors in them! I got to a point (in the photograph) where I could take out a common factor of 1/x but I'm pretty stumped although via other methods I'm almost certain the limit is 1/2 Any help...
10. L'Hospitals Rule for finding the limits of a function

Above is a function which I have been given to take the limits of, now we were briefly introduced to L'Hospitals rule and given this example! Here is what I have done so far......l.. Basically I know that I have to take the derivatives of each of the functions in the quotient and then tend...
11. Interatomic potential and binding energy system of equations

I have attached a photograph of my problem to save time on typing the question I have done the first part to obtain the expression for equilibrium bond length and in the second part I solved that equation for A and substituted it into my binding energy equation and obtained an answer with...
12. Buoyancy - block of concrete is being raised from a lake

Buoyancy -- block of concrete is being raised from a lake Question; A 50kg block of concrete is being raised from a lake. What fraction of its weight in air is required to lift it while submerged? My attempt, I'm pretty sure this question pertains to Archimedes principle I calculated the...
13. Latent heat?

I was looking through my notes and came across this (above) I understand the calculation etc but I don't see where the number of atoms N was calculated? I don't see where it has come from Any help would be great thanks in advanced
14. Ε, concerning latent heat?

This is a question of understanding notes today:) I'm struggling to follow these notes, they are not very well written and a tad sporadic! I was just reading through them and I'm not quite sure what the term ε actually is in this case? I am assuming it is a constant although on the first...
15. Simple harmonic motion (Again)

Simple harmonic motion (Again) :( This is not a question about a problem it is more about the position of a simple harmonic oscillator as a function of time:) I went through it in a lecture yesterday and found using the energy in simple harmonic motion to be x(t)= A cos(ωt +φ) Which is...
16. SHM equation question

I found this example in my physics textbook but it seems that the answers I get when I plug in the numbers are different to what the example says and I'm not so sure why? Image attached of course! It gives the phase as 7.5 which I got but when I used it in the equations I didn't get the...
17. Simple Harmonic Motion (Total Energy)

I have a question about the derivation that I have attached! I understand that both KE and U are 1/2 kA^2 So how is it that the two combine is also equal to 1/2kA^2 Not sure if I'm missing something but I'm a little confused :(
18. Elastic moduli question

Question; The shank of the bold has a diameter of 1.2cm and a head height of 0.8cm. What is the maximum tensile load that the bolt can withstand if it's ultimate shear strength is 3.5*10^8 N/m^2 I have attached a photo of the diagram given in the question. My attempt I noticed that this is...
19. Vector question

I was given an example in a lecture of a vector question which is typical of this module. Question The position of mass m is described as a vector r, from an origin such that r= 7t i + (4t-3t^2) j metres. Find the magnitude and directions of r and dr/dt when dy/dt=0 Now I have worked...
20. Angular kinematics

Question The wheel of a car has radius 0.2m and initially rotates at 120 rpm. In the next minute it makes 90 revolutions What is the cars angular acceleration? Attempt So I tried to get the final angular velocity and couldn't and have tried multiple times with the angular kinematics...
21. Work done by a changing force

I am stuck with the above question, my answer to a is 40J but the model answer is 30J Really frustrating as the book I am ready only goes over straight line graphs
22. Newtons laws

I am a little stumped with this question:( I have attached my solution so far which has just been to deduce the acceleration on the flat surface
23. Friction/ Newtons Laws

Hi I am stuck with a question which I have attached a photo of, it is one involving friction! I have done a few of these questions already and find it is when I am defining forces etc it's where I go wrong, not the easy computational part:( I also have attached my attempt at the solution and...
24. Polarisation past paper question

Question For (i) I assumed that the light was plainly polarised as there is only a difference in amplitude For (ii) There is a negative sign infront of the amplitude which I ignored as it doesn't change the polarisation but one is cos and the other is sin, so there is a phase shift of...
25. Circuit symbol?

I have a circuit and in the circuit there is two over lapping circles and I'm not sure what it is because there is no description or anything. I think it is a current or something but next to it is the symbol gm *Vbe and I know Vbe is the voltage between the base and emitter but what is gm?
26. Parachutist falling

A 60kg parachutist and her 7kg parachute fall at a constant 6m/s Find the force on the woman due to chute? My attempt: All I can gather from this is that the chute and her are not accelerating, so get are at terminal velocity?
27. Components of torque in a solid sphere

A uniform sphere of mass M and radius R has a point on its surface fixed at the origin. Its centre lies along a line in the direction of the position vector r = i + 2k + 3k at length R. Find the components of the torque acting on it due to gravity if the z-direction is upwards and gravity acts...
28. Work done to move a spring

A spiral spring exerts a restoring torque on an axis proportional to the angle through which the axis is turned. If it provides a torque of 10-5 Nmrad-1, find the energy required to turn it through 180degrees from its relaxed state? My solution was simple Work done = torque* the angle theta...
29. Stuck with a projectile question

Question; A rocket launched at 70 degrees to the horizontal has constant net acceleration of 8m/s^2 along its path for 6.5 seconds and then is in free fall! What is the rockets maximum height? Ps answer is 281m I couldn't help but look lol Solution attempt: From the net acceleration I got...
30. Yoyo Problem

Yoyo Problem:( Question: A cylindrical yoyo of mass m and radius R falls a height h from rest. What is its velocity after this fall? My attempt: I drew a diagram and at rest determined that T-mg=ma Where T is tension and acceleration is centripetal acceleration v^2/r So v= sqrt of T-gR...