Estimate how often stars collide in the Milky Way (using the model of a cylinder with radius = disc scale length and height = 2* disc scale height)

Estimate how often galaxies collide in a galaxy cluster, i.e., the stellar component of one galaxy passing through another.(Model the average galaxy as a sphere with a radius of 10 kpc).

A 200 g hockey puck is launched up a metal ramp that is inclined at a 30° angle. The coefficients
of static and kinetic friction between the hockey puck and the metal ramp are #5 = 0.40 and pk =

0.30, respectively. The puck's initial speed is 14.9 m/s. What speed does it have when it slides back
down to its starting point?

questions 1) : How to control the polarization of light and intensity and phase of light ????

questions 2) : How to control the polarization, intensity, phase of liquid crystal ???

As a physics demonstration, you want a special bowling ball made to demonstrate exactly 1 kg·m2, so that your students can rotate the ball about its center of mass to get a "feel" for how "big" 1 kg·m2 is. The bowling balls most familiar to your students has a weight of 15.4 pounds and have a circumference of 25.5 inches, but do not have a moment-of-inertia equal to 1 kg·m2. Since the sporting goods manufacturer has no understanding of how \"big\" 1 kg·m2 is, calculate the diameter of the demo bowling ball (in inches) it will need to manufacture. Assume that bowling balls are solid, with a constant density.

63. Use Max Planck’s quantum theory to explain the following behaviour of photoelectrons.

a) Low-intensity light does not release any photoelectrons. What will happen if the light

is made brighter? Explain your reasoning.

b) Low-intensity light releases photoelectrons. What will happen if the light is made

brighter? Explain your reasoning.

c) Low-intensity light does not release any photoelectrons. What will happen if the

frequency of the light is gradually increased? Explain your reasoning.

3. List some types of optimization algorithms for photons and for protons planning.
Compare the dose distribution of Photon IMRt with the proton IMPT.
How are the organs at risk protected in photon therapy and how are in Proton therapy?

Two events are observed by inertial observer Stampy to occur a spatial distance of 15 c·s apart with the spatial coordinate of the second larger than the spatial coordinate of the first. Stampy also determines that the second event occurred 17 s after the first. According to inertial observer Philip moving along Stampy’s +x axis at unknown velocity v, the second event occurs 10 s after the first. (1 c·s = 1 light-second = unit of distance.)

a) Given Philip measures the spatial coordinate of the second event to be larger than the first, determine v.

b) How far apart spatially (in c·s) do the two events occur according to Philip?

c) Does there exist an inertial reference frame v < c in which the second event can occur before the first? Briefly explain in one sentence at most.
d) Inertial observer Kenny observes the proper time between the two events. How fast along Stampy’s +x axis does Kenny move?

(Note: Each part of this question can be done independently of any other. In part a, depending on how you solve it, you might obtain two answers as solutions of a quadratic, but one of them is extraneous, because it violates the premise in part a. If you are careful, you can avoid the quadratic at the outset, but it requires you to solve part b first.)

Could you put the helium nucleus (also known as an "alpha particle") somewhere on a line between the proton and electron where it wouldn't feel a net force? Why or why not?

A tortoise and hare start from rest and have a race. As the race begins, both accelerate forward. The hare accelerates uniformly at a rate of 1.2 m/s² for 4.4 seconds. It then continues at a constant speed for 11.8 seconds, before getting tired and slowing down with constant acceleration coming to rest 81 meters from where it started. The tortoise accelerates uniformly for the entire distance, finally catching the hare just as the hare comes to a stop.

1)

How fast is the hare going 3.1 seconds after it starts?   See solution

2)

How fast is the hare going 12.5 seconds after it starts?
See solution

3)

How far does the hare travel before it begins to slow down?

m

4)

What is the acceleration of the hare once it begins to slow down?

m/s²

5)

What is the total time the hare is moving?

s

6)

What is the acceleration of the tortoise?

m/s²

In a student experiment, a constant-volume gas thermometer is calibrated in dry ice (−78.5°C) and in boiling ethyl alcohol (78°C). The separate pressures are 0.896 atm and 1.629 atm. Hint: Use the linear relationship P = A + BT, where A and B are constants.

(a) What value of absolute zero does the calibration yield?

(b) What pressure would be found at the freezing point of water?

(c) What pressure would be found at the boiling point of water?

Please answer the following questions clearly.

1) If two quantum states differ only by a phase factor, are they considered the same ? if so in what sense ?

2) Explain entaglement quickly?

3) why is the composite of quantum states is given by a tensor product whereas the composite of a classical states is given by a Cartesian product?

Two spheres have the same diameter and mass, but one is solid and the other one is hollow. Assuming homogeneous densities and putting the origin at the center, calculate the inertia tensor of each sphere.

What are the steps that you need to take when solving a problem using Ampere's Law?

(a) (i) What particles inside of an atom make the biggest contribution to its magnetic moment? (ii) What are the two types of angular momentum that are involved?

(b) You are given a “term” 3P. (i) What is it describing? (ii) What values are associated with it? (iii) Is it a type of coupling? If so what kind?

(c) ( What if you instead say 3P2? (i) What is this called? (ii) What is the meaning of the extra label?

(d) ( These correspond to electron configurations with 2 electrons in three p suborbital. (The usual notation with 2 arrows.) (i) Fill in the arrows (electrons) to give one configuration that is part of 3P term. (ii) Give a configuration that violates Pauli exclusion.