A 50-kg block rests on a horizontal surface. The coefficient of static friction u(s) = 0.50. The coefficient of kinetic friction u(k) = 0.35. A force of 250 N is applied as shown (to the right). ***Please show all work and how to tell if accelerates or moves at constance velocity.*** A) The block remains at rest. B) The block moves and continues to move at a constant velocity. C) The block accelerates to the right. D) The block doesn't move until Force is increased to greater than 490N. E) No conclusions can be drawn concerning the movement of the block from the information given.

A macro lens is designed to take very close-range photographs of small objects such as insects and flowers. At its closest focusing distance, a certain macro lens has a focal length of 33.0 mm and forms an image on the photosensors of the camera that is 1.19 times the size of the object.

1) How close must the object be to the lens to achieve this maximum image size? (Express your answer to three significant figures)

2) What is the magnification if the object is twice as far from the lens as in part (1)? (Express your answer to three significant figures.)

3) The momentum eigenfunction for a particle moving in one dimension is фр--h-1/2eipz/n The energy eigenfunction for a particle in a 1D box of length L is u()- is expanded in terms of фе(x), the expansion coefficient may be interpreted as the momentum probability amplitude; its square gives the probability density for momentum. Determine the momentum probability density for u(x)

A magnetic field is perpendicular to the plane of a single-turn circular coil. The magnitude of the field is changing, so that an emf of 0.25 V and a current of 2.5 A are induced in the coil. The wire is then re-formed into a single-turn square coil, which is used in the same magnetic field (again perpendicular to the plane of the coil and with a magnitude changing at the same rate). What (a) emf and (b) current are induced in the square coil?

A small He-Ne laser produces a 632.8 nm beam with an average power of 3.5 mW and diameter of 2.4mm

a) How many photons per second are emitted by the laser?
b) What is the amplitude of the electric field inside the beam? (Hint: You should consult your EP book, the internet, or equation 3.10 for this problem)
c) How does this electric field compare with one produced by a 100W light bulb at a distance of 1 meter?

A 1150 kg car drives up a hill that is 15.7 m high. During the drive, two nonconservative forces do work on the car: (i) the force of friction, and (ii) the force generated by the car's engine. The work done by friction is −2.91×105 J ; the work done by the engine is 6.74×105 J . Find the change in the car's kinetic energy from the bottom of the hill to the top of the hill.

Which method(s) of energy transfer does not require matter? Which method(s) of energy transfer does require matter? Give an example of each

A monatomic ideal gas expands slowly to twice its original volume, doing 430 J of work in the process.

A) Find the change in internal energy of the gas if the process is isothermal.

B) Find the heat added to the gas if the process is adiabatic.

C) Find the change in internal energy of the gas if the process is adiabatic.

D) Find the heat added to the gas if the process is isobaric.

E) Find the change in internal energy of the gas if the process is isobaric.

the spacecraft Discovery 1 has gotten too close to a black hole! The ship has a large rear section containing the nuclear engines, with a mass of 3,000 kg; a front section for the crew quarters, also with a mass of 3,000 kg; and a thin, essentially massless 100 m-long steel frame between their centers of mass, to keep the crew as far as possible from the engines’ radiation.

The ship is pointing directly away from the black hole, firing its engines at maximum thrust to try to escape. The black hole is 10 times the mass of the Sun.

(a) The nuclear thermal rocket engines can consume up to 10. kg/s of fuel, expelling it from the thrusters with a velocity of 8.0 km/s. What force they can provide? (If you need to review rocket thrust, it’s covered in Chapter 9.)

(b) When it’s still 1 million km away, what is the gravitational force of the black hole on the entire ship? Can it escape??

(c) When the rear of the ship is 10,000 km from the black hole, what is the gravitational force on the rear section? What is the force on the front section? Write down as many digits as needed to show that they differ.

(d) The difference in force between the two sections will cause tension on the long frame connecting them. The frame has a cross-sectional area of 100 cm2 and is made of steel. By how much does it stretch?

(e) If it stretches by more than 10 cm, it will snap. What is the distance from the hole at which the ship breaks apart? If you can’t solve for the answer directly, you can always try plugging in various distances to narrow in on an approximate value.

(f) In a class whiteboard problem, we derived the radius around a black hole at which the escape velocity is equal to the speed of light. The surface at this radius is known as the event horizon. It is not a solid surface, but simply the line beyond which there is no possible return. Will the Discovery 1 break apart before falling through the horizon?

A particle with a charge of -60.0 nC is placed at the center of a non-conducting spherical shell of inner radius 20.0 cm and outer radius 25.0 cm. The spherical shell carries charge with a uniform volume density of -1.33 μC/m3. A proton moves in a circular orbit just outside the spherical shell. Calculate the speed of the proton.

A mass is placed on a frictionless, horizontal table. A spring ( k = 185 k=185 N/m), which can be stretched or compressed, is placed on the table. A 4.5-kg mass is anchored to the wall. The equilibrium position is marked at zero. A student moves the mass out to x = 7.0 x=7.0 cm and releases it from rest. The mass oscillates in simple harmonic motion. Find the position, velocity, and acceleration of the mass at time t = 3.00 t=3.00 s. Round all of your answers to one decimal place.

In a nuclear fission reactor, each fission of a uranium nucleus is accompanied by the emission of one or more highspeed neutrons, which travel through the surrounding material. If one of these neutrons is captured in another uranium nucleus, it can trigger fission, which produces more fast neutrons, which could make possible a chain reaction. However, fast neutrons have low probability of capture and usually scatter off uranium nuclei without triggering fission. In order to sustain a chain reaction, the fast neutrons must be slowed down in some material, called a “moderator.” For reasons having to do with the details of nuclear physics, slow neutrons have a high probability of being captured by uranium nuclei.

A slow neutron induces fission of U-235, with the emission of additional (fast) neutrons. The moderator is some material that slows down the fast neutrons, enabling a chain reaction.

In the following analyses, remember that neutrons have almost no interaction with electrons. Neutrons do, however, interact strongly with nuclei, either by scattering or by being captured and made part of the nucleus. Therefore you should think about neutrons interacting with nuclei (through the strong force), not with entire atoms.

1. Based on what you now know about collisions, explain why fast neutrons moving through a block of uranium experience little change in speed.

2. Explain why carbon should be a much better moderator of fast neutrons than uranium.

3. Should water be a better or worse moderator of fast neutrons than carbon? Explain briefly.

A transverse sinusoidal wave is generated at one end of a long, horizontal string by a bar that moves up and down through a distance of 1.7 cm. The motion is continuous and is repeated regularly 160 times per second. The string has linear density 460 g/m and is kept under a tension of 140 N. Find the maximum value of (a) the transverse speed u and (b) the transverse component of the tension T. (c)Show that the two maximum values calculated above occur at the same phase values for the wave. What is the transverse displacement y of the string at these phases? (d) What is the maximum rate of energy transfer along the string? (e) What is the transverse displacement y when this maximum transfer occurs? (f ) What is the minimum rate of energy transfer along the string? (g) What is the transverse displacement y when this minimum transfer occurs?

A.)

In the lab, you will determine a value for the time constant of the RC circuit, by measuring the amount of time it takes the capacitor voltage to increase from 0.0 V to ______ % of its maximum value.

B.)

If you only have capacitors of one value, you can change the total capacitance of the circuit by using combinations of capacitors. Assuming that all the capacitors have the same value, how could you increase the total capacitance?

Options: