4 Neutron interactions within nuclear power systems.

a) Explain with quantification the terms ‘thermal’ and ‘fast’ to describe neutrons.

b) Describe fully three important neutron interactions in a thermal nuclear power reactor.

c) Describe the range of materials in which these neutron interactions occur and their function in a nuclear reactor.

d) Explain the criticality of the power generation process in terms of these reactions and give a relevant equation with explanation.

The average resistivity of the human body (apart from surface resistance of the skin) is about 5.0 Ω⋅mΩ⋅m. The conducting path between the right and left hands can be approximated as a cylinder 1.6 mm long and 0.10 mm in diameter. The skin resistance can be made negligible by soaking the hands in salt water. If skin resistance is negligible, what potential difference between the hands is needed for a lethal shock current of 100 mAmA? (Your result shows that even small potential differences can produce dangerous currents when the skin is damp.)

Gayle runs at a speed of 3.30 m/s and dives on a sled, initially at rest on the top of a frictionless snow-covered hill. After she has descended a vertical distance of 5.00 m, her brother, who is initially at rest, hops on her back and together they continue down the hill. What is their speed at the bottom of the hill if the total vertical drop is 15.0 m? Gayle's mass is 46.0 kg, the sled has a mass of 5.05 kg and her brother has a mass of 30.0 kg.

If there was no energy generated in the solar interior the core of the Sun would ...

Question 1 options:

Question 2 (1 point)

All other things being equal, which of the following conditions would result in more nuclear reactions taking place each second inside the Sun than is currently the case ?

Question 2 options:

Question 3 (1 point)

What part of the Sun do astronomers learn about when they study neutrinos from the Sun

Question 3 options:

Determine the area of a flat piece of metal according to the data in the table below. The answer will need to be correctly stated as: (mean value ± σ_m) units. For example: Area = (3.2 ± 0.2 cm²).

(a)

Determine the mean, standard deviation, and the standard deviation of the mean for the measurements. (Hint: Use Logger Pro to help you make the calculations. Enter your mean values to at least four decimal places, and enter your standard deviations to at least five decimal places.)

A place-kicker must kick a football from a point 36.0 m (about 40 yards) from the goal. Half the crowd hopes the ball will clear the crossbar, which is 3.05 m high. When kicked, the ball leaves the ground with a speed of 22.4 m/s at an angle of 47.0° to the horizontal. (a) By how much does the ball clear or fall short (vertically) of clearing the crossbar? (Enter a negative answer if it falls short.) m (b) Does the ball approach the crossbar (and cross above or beneath it) while still rising or while falling?

Comparison of electric & gravity forces: Two identical blocks are placed 5 m apart. Each has a mass of 2 kg, is electrically neutral, and is made entirely of copper. Note: One copper atom has a mass of 1.055·10-25 kg and contains 29 protons. a.) How many electrons must a neutral copper atom have? 29 Correct: Your answer is correct. electrons b.) Estimate the percentage of a copper atom's mass that is due to: electrons: 0.025 Correct: Your answer is correct. % protons: 45.9 Correct: Your answer is correct. % Do a proton & electron have an equal amount of charge? Of mass? Also, what constitutes the remaining mass of these copper atoms? c.) Estimate how many electrons each of these blocks has within it. 5.50e26 Correct: Your answer is correct. electrons What is the total charge of all these electrons? -8.8e7 Correct: Your answer is correct. C And what is the total charge of all the protons in a block? +8.8e7 Correct: Your answer is correct. C So what is the net charge of each block? 0 Correct: Your answer is correct. C d.) You now remove an equal amount of electrons from each block, so the electric repulsion of the blocks cancels their gravitational attraction to each other. (Note: You may assume the mass of the blocks is not significantly reduced when removing these electrons-- why?) What is the net charge of each block now? 1.72e-10 Correct: Your answer is correct. C How many electrons were removed from each block? Give a number, and then also express this as a percentage of the total number in the block. % Did your answers for this part depend on the distance between the blocks?

Water standing in the open at 34.5°C evaporates because of the escape of some of the surface molecules. The heat of vaporization (553 cal/g) is approximately equal to εn, where ε is the average energy of the escaping molecules and n is the number of molecules per gram. (a) Find ε. (b) What is the ratio of ε to the average kinetic energy of H₂O molecules, assuming the latter is related to temperature in the same way as it is for gases?

A spherical conductor has a radius of 14.0 cm and a charge of 26.0 µC.

Calculate the electric field and the electric potential at:

(a) r = 10.0 cm,

(b) r = 20.0 cm,

(c) r = 14.0 cm from the center.

A contestant in a winter games event pushes a 46.0 kg block of ice across a frozen lake as shown in the figure below. The coefficient of static friction is 0.1 and the coefficient of kinetic friction is 0.03. (Assume θ = 25°.) (a) Calculate the minimum force F (in N) he must exert to get the block moving. 49.7 Correct: Your answer is correct. N (b) What is its acceleration (in m/s2) once it starts to move, if that force is maintained? Incorrect: Your answer is incorrect. Consider Newton's Second Law. m/s2

The ammonia molecule NH₃ has a permanent electric dipole moment equal to 1.47 D, where 1 D = 1 debye unit = 3.34 × 10^-30 C-m. Calculate the electric potential in volts due to an ammonia molecule at a point 49.6 nm away along the axis of the dipole. (Set V = 0 at infinity.)

Answer following questions:

a) Explain the difference between an isotropic material and an anisotropic material. Give one example of abiological material other than bone that is anisotropic and explain how it is anisotropic.

b) It is well documented that humans are typically taller first thing in the morning, but get progressively shorter (by very small amounts) as the day goes on. Based on what you know about the viscoelastic properties of human body tissues, can you explain this phenomenon?

c) Explain how the creep response of a viscoelastic material is different than the stress-relaxation response of that material. Provide an example of one biological material for which creep is a significant issue to deal with and one biological material for which stress-relaxation is a significant issue to deal with.

Ball Thrown upward with an initial speed of 14.7m/s from a height of 89m

a)Draw the sketch of this motion

b) State the theory that describes this motion

c) Write the velocity and position kinematics equations with the number obtained from the sketch

d) Solve all unknowns

- Final velocity

- How long it takes that ball hit the ground

- Maximum Height

- Acceleration (I think its gravity)

e) Draw the velocity vs time and position vs time graphs