A space station is approximately a ring of radius,R, and mass m, which rotates about its symmetry axis with angular velocity,~ω=ω0ˆe3. A meteor is traveling with momentum,~p, that is parallel to the original ˆe3, and strikes the space station at a point on the rim,transferring the entire momentum to the space station (an inelastic collision where the meteor sticks to the space station). Further, though the meteor has significant momentum,it is of very small mass so that the moment of inertia tensor elements are approximately the same before and after the collision

a) What is the vector angular momentum of the space station with respect to a coordinate system with origin at the center of the ring and one axis along ˆe3 just before the collision?

b) What is the vector angular momentum of the space station in the same coordinate system (and defining the ˆe2 axis as in the direction from the origin to the point of impact on the edge of the ring) just after the collision?

c) After the collision, there are no further torques acting on the space station. Assume that the angular momentum of the space station after the collision differs by only a small (vector) amount from the initial angular momentum. Write down equations of motion that describe how the components of~ωfor the space station evolve with time.

d) Use these equations to describe how the rotational velocity vector of the space station evolves with time. If you predict simple rotation about a new direction, say so and describe the new direction. If you predict precessional motion, say so and predict the precession frequency. If you think something else happens, say so and describe the motion. In all cases, Explain: Back up your prediction with reasoning and (possibly approximate) solutions of the equations from part (c).

A potential difference of 4.50 kV is established between parallel plates in air.

If the air becomes ionized (and hence electrically conducting) when the electric field exceeds 3.05×10⁶ V/m , what is the minimum separation the plates can have without ionizing the air?

Answer in mm.

(a) How much work is required to compress 4.92 mol of air at 19.9

Briefly explain the two postulates of relativity, how they differed from classical physics, and

why Einstein was led to propose them. List at least 2 implications of the postulates.

How to find the central pressure of Jupiter? Assuming we know the mass of the Jupiter.

What is light? You can start by describing the different historic models for light and explain their individual strength and shortcomings in explaining observable phenomena. Then, try to summarize our current quantum mechanic understanding and highlight its implications for all matter and energy. Finally, consider identifying visible light within the electromagnetic (EM) spectrum and discuss applications that may depend on different light effects such as photoelectric or electro-luminescent effect.

Problem 1 Two friends are planning to go on a 480 mile-long bike ride over the summer. One is planning to ride a mountain bike with 26-in. tires, the other has a touring bike with 27-in. tires. a) How many more revolutions will the mountain bike tires make in that distance than the touring bike? b) Typical gearing for moste bicycles ranges from 30 to 50 teeth on the chain wheel (front gears) and 12 to 30 teeth on the rear cog. How many more revolutions on the pedals will the mountain biker make during the trip. Assume he is pedaling 85% of the time and has a 42-tooth chain wheel and a 21-tooth rear cog. c) If both cyclists have 170-mm cranks on their bikes, what will be the mechanical advantage (consider only the movement of the feet with a constant force for walking and riding), in percent, that each rider will have achieved over walking the same distance.

Density of modes. The essentials of calculating the number of modes of vibration of waves confined to a cavity may be understood by considering a one-dimensional example. (a) Calculate the number of modes (standing waves of different wavelength) with wavelengths between 2.0 cm and 2.1 cm that can exist on a string with fixed ends that is 2 m long.

(b) Calculate, in analogy to our three

dimensional calculation, the number of modes per unit wavelength per unit length, .

(c) Show that in general the number of modes per unit wavelength per unit length for a string of length L is given

^{Wi-Fi RF Linearization} can you explain this topic in a simple way to make me understand it ?

Materials Science: Composites (Chapter 16)

How do we predict the stiffness and strength of the various types of composites?

Include an original free body diagram and an original extended free body diagram representing the ideal disposition of the four main forces acting on an aeroplane during the five different stages of flight. Explain your diagrams and describe the effect of each of these forces in the aeroplane translation and rotation. Include the angle of attack.

The emission wavelength lies between 275 nm and 450 nm and the light yield per neutron is reported to be 20000 photons/MeV neutron energy

(a) What largest work function of a material used for a photo cathode would be acceptable that still allows detection of an emission originating from the scintillator?

(b) What is the maximum kinetic energy of electrons emitted from the photo cathode, given the emission wavelength range of the scintillator?

(c) How much charge is being generated per single neutron, assuming a 3 MeV neutron and a photon-to-electron conversion efficiency (quantum efficiency) of 15%? Would this charge be detectable if you use an Electrometer2 that has a resolution limit of 10 fC?