Are nuclear reactors safe?
• Discuss the pros and cons of the fission, breeder, and fusion reactors.

• Are you in favor of any form of nuclear energy? Defend your answer.

Chad got a new unpaid internship working in a coal mine pushing minecarts. All his minecarts

are loaded to weigh 340 kg.

(a) He first pushes a cart from rest on a frictionless section of track with a constant force of 300 N

for a distance of 10 m. How much work does he do on the cart? In what form is this energy?

What is the final speed of the cart?

(b) Then, starting from rest, he pushes another cart with the same 300 N a distance of 10 m up

a frictionless 5 degree slope (pushing in the parallel-to-surface direction). How much work

does he do on the cart? How much of this energy is in what forms?

(c) Now he pushes a cart from rest with force 300 N a distance of 10 m on a flat surface with

μs = μk = 0.05. How much work does he do on the cart? How much of this energy is in what

forms?

A: Three forces act on a moving object. One force has a magnitude of 86.0 N and is directed due north. Another has a magnitude of 64.5 N and is directed due west. What must be the magnitude and direction of the third force, such that the object continues to move with a constant velocity?

B: A worker stands still on a roof sloped at an angle of 39.1° above the horizontal. He is prevented from slipping by a static frictional force of 372 N. Find the mass of the worker.

An open container holds ice of mass 0.545 kg at a temperature of -19.4 ∘C . The mass of the container can be ignored. Heat is supplied to the container at the constant rate of 850 J/minute .

The specific heat of ice to is 2100 J/kg⋅K and the heat of fusion for ice is 334×103J/kg.

(A) How much time tmelts passes before the ice starts to melt? answer in minutes

(B) From the time when the heating begins, how much time trise does it take before the temperature begins to rise above 0∘C? answer in minutes

Suppose two plates lie in parallel horizontal planes, one plate in the xy plane at  z = 0 and the other plate in the plane that is parallel to the xy plane at z = 10 mm. Between the plates is a constant electric field directed vertically upward (that is, in the positive z direction). A proton and an electron are launched in the positive x direction with the same initial velocity from position (0, 0, 5.0 mm).

Part A :If the proton strikes a plate at (190 mm , 0, 10 mm), where does the electron strike?

Three bullets are fired simultaneously by three guns aimed toward the center of a circle where they mash into a stationary lump. The angle between the guns is 120°. Two of the bullets have a mass of 4.30 10-3 kg and are fired with a speed of 257 m/s. The third bullet is fired with a speed of 559 m/s and we wish to determine the mass of this bullet in kg

Part I

An object is through from the origin at an initial velocity of v₀ and at an angle θ in relation to the horizon.

a. write out r^->(t) for the object

b. find the velocity vector and acceleration vector for the object.

c. calculate the angle between the velocity vector and the acceleration vector at any point in time t.

Part II

An object is moving upwards on a slope at initial velocity v₀. There is friction between the object and the slope.

a. Calculate the amount of time it will take for the body to return to its initial position.

b. what is the ratio between the final velocity and the initial velocity?

Thank you!

A baseball player is 98m away from home plate when he throws the ball at a 30° angle above horizontal from a height of 1.45 m (the height of his hand).

a. What is the initial speed of the throw for the ball to land exactly on home plate? In order to solve this problem, set up equations for x and y position vs time. Put in all known values. You will have two remaining unknowns: v0(the magnitude of the initial velocity) and t. Solve the system of equations.

b.How long does it take the ball to get to home plate?

c.What is the maximum height that the ball is above the ground?

d. Sketch with coordinate system

Radioactive isotopes often occur together in mixtures. Suppose a 220g sample contains ¹³¹Ba, with a half-life of 12 days, and ⁴⁷Ca, with a half-life of 4.5 days.

If there are initially twice as many calcium atoms as there are barium atoms, what will be the ratio of calcium atoms to barium atoms 2.10 weeks later?

N_Ca/N_Ba = ?

Suppose a crate of mass 8.8 kg is placed on the plank in the figure below at a distance x = 6.3 m from the left end. If the plank has a mass of 12 kg, find the forces exerted by the two supports on the plank. (Indicate the direction with the sign of your answer.)

I need to know the steps of solution for part (b,c,d) I have been trying for almost 2 days.

A 195 -keV X-ray photon coherently scatters off one of the valence electrons of a nitrogen atom. Assume that the scattering angle of the photon is ? = 15

What are the advantages and disadvantages of collecting observational data on a sport skill during a competitive event as opposed to a practice session

Two identical, small insulating balls are suspended by separate 0.21-m threads that are attached to a common point on the ceiling. Each ball has a mass of 7.4 x 10-4 kg. Initially the balls are uncharged and hang straight down. They are then given identical positive charges and, as a result, spread apart with an angle of 50 degrees between the threads. Determine (a) the charge on each ball and (b) the tension in the threads.

A 29.3 L sample of air at 31.5% contains 0.275g of water vapor. What is the relative humidity of the air, if the vapor pressure of water at this temperature is 34.8 torr? Answer must contain proper significant figures

A pipe contains water that has a flow rate of 475 gal/min. If water is flowing with a velocity of 2.5m/s, what is the diameter of the pipe in meters? Answer must contain the proper significant figures

A swimming pool of width 9.0m and length 24.0m is filled with water to a depth of 3.0m. Calculate pressure on the bottom of the pool due to the water. Assume that the atmospheric pressure is 741 torr and the density of water is 1.0045g/cm3. Answer must contain the proper significant figures.

Krypton gas (Kr) and an unknown gas are mixed in a container with a small hole in the side. The Kr gas escapes from the container at a rate of 0.882ml/s. The unknown gas escapes from the container at a rate of 1.5256mL/s. What is the molar mass of the unknown gas? If the gas is a diatomic made of two identical atoms, what is the unknown gas? Answer must contain the proper significant figures.