At Enormous State University (ESU), the football team records its plays using vector displacements, with the origin taken to be the position of the ball before the play starts. In a certain pass play, the receiver starts at +1.5 i^ - 3.0 j^, where the units are yards, i^ is to the right, and j^ is downfield. Subsequent displacements of the receiver are +7.5i^ (in motion before the snap), +10 j^ (breaks downfield), ?6.0i^+4.0j^ (zigs), and +12.0i^+18.0j^ (zags). Meanwhile, the quarterback has dropped straight back to a position ?7.0j^.

Part A

How far must the quarterback throw the ball? (Like the coach, you will be well advised to diagram the situation before solving it numerically.)

Express your answer using two significant figures.

Part B

In which direction must the quarterback throw the ball?

Express your answer using two significant figures.

Is Teflon radiodense or radiopaque? Can a CT scan penetrate a thin layer of Teflon?

A diverging lens has a focal length of 18.6 cm .

A. What is the image distance for an object distance of 37.2 cm? Answer with −1000 cm if no image is formed. What is the magnification?

B. What is the image distance for an object distance of 18.6 cm? Answer with −1000 cm if no image is formed. Answer in units of cm. What is the magnification?

C. What is the image distance for an object distance of 9.3 cm? Answer with −1000 cm if no image is formed. Answer in units of cm. What is the magnification?

Calculate the binding energy per nucleon for the following isotopes.

(a) ¹²C
______MeV/nucleon

(b) ¹¹B
________MeV/nucleon

(c) ⁵⁵Mn
________MeV/nucleon

(d) ¹⁹⁵Pt
_______MeV/nucleon

Neutrons from a source (such as beryllium bombarded with particles from radium or plutonium) bombard natural palladium, which is 27% 106Pd. What is the energy output of the reaction 106Pd + n 107Pd + γ? The mass of 106Pd is given in Appendix A, and that of 107Pd is 106.905129 u.

A diverging lens with a focal length of -13 cm is placed 12 cm to the right of a converging lens with a focal length of 21 cm . An object is placed 40 cm to the left of the converging lens. Where will the final image be located?Where will the image be if the diverging lens is 41 cm from the converging lens?

A mass m = 13 kg is pulled along a horizontal floor with NO friction for a distance d =7.4 m. Then the mass is pulled up an incline that makes an angle θ = 32° with the horizontal and has a coefficient of kinetic friction μ_k = 0.31. The entire time the massless rope used to pull the block is pulled parallel to the incline at an angle of θ = 32° (thus on the incline it is parallel to the surface) and has a tension T =59 N.

What is the work done by tension before the block goes up the incline? (On the horizontal surface.)

What is the speed of the block right before it begins to travel up the incline?

What is the work done by friction after the block has traveled a distance x = 4.1 m up the incline? (Where x is measured along the incline.)

What is the work done by gravity after the block has traveled a distance x = 4.1 m up the incline? (Where x is measured along the incline.)

How far up the incline does the block travel before coming to rest? (Measured along the incline.)

On the incline the net work done on the block is:

positive

negative

zero

A crate of mass 9.4 kg is pulled up a rough incline with an initial speed of 1.52 m/s. The pulling force is 110 N parallel to the incline, which makes an angle of 20.8° with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 4.92 m.

(a) How much work is done by the gravitational force on the crate? J

(b) Determine the increase in internal energy of the crate–incline system owing to friction. J

(c) How much work is done by the 110-N force on the crate? J

(d) What is the change in kinetic energy of the crate? J

(e) What is the speed of the crate after being pulled 4.92 m?

Thank you so much for your help! An explanation of each would be greatly appreciated!!

Two wooden crates rest on top of one another. The smaller top crate has a mass of m₁ = 18 kg and the larger bottom crate has a mass of m₂ = 85 kg. There is NO friction between the crate and the floor, but the coefficient of static friction between the two crates is μ_s = 0.82 and the coefficient of kinetic friction between the two crates is μ_k = 0.66. A massless rope is attached to the lower crate to pull it horizontally to the right (which should be considered the positive direction for this problem).

A)The rope is pulled with a tension T = 406 N (which is small enough that the top crate will not slide). What is the acceleration of the small crate?
B)In the previous situation, what is the frictional force the lower crate exerts on the upper crate?
C)What is the maximum tension that the lower crate can be pulled at before the upper crate begins to slide?
D)The tension is increased in the rope to 1185 N causing the boxes to accelerate faster and the top box to begin sliding. What is the acceleration of the upper crate?
E)As the upper crate slides, what is the acceleration of the lower crate?

I am in AMO Physics and work a lot with optics. I just wanted to get an idea of what coupling efficiencies one "should" get in a "reasonable time"* by coupling light into a fiber using different couplers, like collimators, mounting plates, mounted lens systems, etc. I understand that this dependents on a lot of factors, so I will narrow it down for my specific case but would appreciate if ppl report some numbers with a short info about their setups.

We use a cage system system with 5 mm lens and APC fiber plate to couple 633 nm laser light into an APC single mode fiber. Pretty much everything of the optical equipment is from Thorlabs.com.

The reason for my question: My PI told me I should get efficiencies up 80% percent with our coupling scheme but I can only get 30%. I hope to get a better feeling for coupling efficiencies with this answer.

Thanks for your input,

n3rd

*With "should" and "reasonable time" I refer to coupling efficiencies one can achieve at time scales on the order of tens of minutes rather than hours, days, weeks.

There was an old argument by Landau that while the liquid gas transition can have a critical point, the solid-liquid transition cannot. This argument says that the solid breaks translational symmetry, and it is impossible to do this in a second order transition.

But this argument is subtly false. Second order transitions break symmetries, which can be discrete, like in the Ising model, or continuous, like in the x-y model. The reason Landau said it is because it is hard to imagine breaking all the translational and rotational symmetries all at once to make a second order liquid-solid point.

But nowadays we know about nematics, and we can imagine the following chain of second-order transitions:

fluid (I)-> fluid with broken x-y-z rotational symmetry with a z-directional order (II) -> fluid broken translational symmetry in the same direction -> broken x-y direction rotational symmetry in the y-direction -> broken y- direction translational symmetry -> broken x-direction translational symmetry

Each of these transitions can be second order, and together, they can make a solid from a fluid. the question is, how badly does Landau's argument fail.

Are there any two phases which cannot be linked by a second order phase transition?
Are there always parameters (perhaps impossible to vary in a physical system) which will allow the second order points to be reached?
Is it possible to make the second order transitions collide by varying other parameters, to bring them to one critical point (in the example, a critical point between fluid and solid).
Do these critical points exist in any system?

Choose the correct statement in the parentheses.

• If an object has a constant velocity, there (must, may, or cannot) be a net force acting on it.
• If an object accelerates, there (must, may, or cannot) be a net force acting on it.
• If an object remains at rest, there (must may, or cannot) be a net force acting on it.
• If an object moves, there (must, may, or cannot) be a net force acting on it.

• The less mass a moving object has, the (harder, easier, none of the above) it is to stop it.
• The more mass an object at rest has, the (harder, easier, none of the above) it is to make it move.
• The more mass a moving object has, the (harder, easier, none of the above) it is to keep it moving.

a 20 kg super ball is rolling along a level road at a velocity of 5 m/s. it elastically collides head-on with a 10kg super ball initially at rest. find the final velocities of each ball after the collision and show that the collision is, in fact, elastic.

The angular velocity of flywheel decreases uniformly from 12000rev/min to 3000 rev/min in 8 sec. Find theangular acceleration and the number of revolutions made by the wheel in the 8 sec interval. How many more seconds are required for the wheel to come to rest?

4.40 g of nitrogen gas at 18.0 ∘C and an initial pressure of 3.00 atm undergo an isobaric expansion until the volume has tripled.

Part A

How much heat energy is transferred to the gas to cause this expansion?

Express your answer with the appropriate units.

Part B

The gas pressure is then decreased at constant volume until the original temperature is reached. What is the gas pressure after the decrease?

Part C

What amount of heat energy is transferred from the gas as its pressure decreases?