Radioactive iodine is given to patients to reduce thyroid growth or activity. The iodine I₅₃¹³¹, has a half-life of 8.04 days. Why would the radiation in the human body decrease at a faster rate than at the calculated rate?

A nail contains trillions of electrons. Given that electrons repel from each other, why do they not fly out of the nail?

Nuclear fission reactors consist of three main components: the fuel rods, control rods and the moderator. Draw a diagram of typical reactor and give a brief description of each of the main components. Why are fusion reactors considered ‘cleaner’ than fission reactors?

2. A 10 kg ball moving to the right with a speed of 6.0 m/s collides with a 20 kg ball moving to the left at a speed of 4.0 m/s.

(a) If this is a head-on, perfectly inelastic collision, what is the velocity of the balls after the collision. Give magnitude and direction. (5 pts.)

(b) If this is a head-on collision and the the 10 kg ball moves to the left with a speed of 7.0 m/s after the
collision, what is the velocity of the 20 kg ball after the collision? Give magnitude and direction.

(c) Is the collision in part b perfectly elastic? (You must show a calculation here.) (5 pts.)

(d) If the balls are in contact for 0.03 seconds during the collision in part (b), what is the magnitude of
the average force that each ball exerts on the other? (5 pts.)

(e) Write an equation for conservation of momentum in the x direction and determine the x component of the
velocity of the 20 kg mass. (5 pts.)

(f) Write an equation for conservation of momentum in the y direction and determine the y component of the

velocity of the 20 kg mass. (5 pts.)

A plane of area 0.25m2and surface charge density s=4.5 nC/m2 lies in the x = 0.00 m plane, and a second plane of surface charge density s= -4.50 nC/m2 lies in the x = 0.0200 m plane. Find:a.find the capacitance, the stored charge, and the potential energy of the system. b.the electric potential difference between the 2 planes.c.the electric field at (i) x = 0.0180 m and (ii) x = 0.0500 m (508 N/C and 0 N/C). d.What is the maximum charge that this capacitor can hold before it breaks down? e. A charged particle of mass 6.64x10-27kg travels the distance two charged plates in 2.84x 10-7s. Find the charge of the particle.

*Please don't forget to answer part E. Thank you!

A block of mass m = 2.6kg is attached to a single spring of spring constant k = 4.4Nmand allowed to oscillate on a horizontal, frictionless surface while restricted to move in the x-direction. The equilibrium position of the block is x=0m. At time t=0s the mass is at position x=2.7m and moving with x-component of velocity vx=−6.8ms. What is the x-component of velocity at time t=1.3s? Answer in meters per second.

does accleration increase down an inclined plane

Estimatethe total entropy change when 100.g of liquid water, initially at 298 K and 0.50 atm,is first heated to boiling at 373 K and 1.00atm, and the steamcollected at 1.00 atmsubsequently heated and compressed to 500Kand20.atm. UseDHvap(at 100 ̊C, 1 atm)= 40.6 kJ/mol and the following values for the heat capacity:CP,m(H2O,l) = 75.2 J/(K mol), CP,m(H2O,g) = 35.0J/(K mol)

Describe, in detail, what would happen if you fell into a black hole, from both your perspective, and the perspective of someone who is watching you fall in. You should include specific effects, including effects on space, time, and what you would see.

For hydrogen, an ionized helium ion He⁺, and a doubly ionized lithium ion Li²⁺, calculate:

(a) The radii of the first and second Bohr orbits and the velocities of electrons in these orbits.

(b) The binding energy of an electron in their ground states.

(c) The first excitation energy and the wavelength of their resonance lines.

An electric vehicle starts from rest and accelerates at a rate of 2.4 m/s² in a straight line until it reaches a speed of 27 m/s. The vehicle then slows at a constant rate of 1.4 m/s² until it stops. (a) How much time elapses from start to stop? (b) How far does the vehicle move from start to stop?

A retaining wall against a mud slide is to be constructed by placing 1.2 m-high rectangular concrete blocks (ρconcrete = 2700 kg/m3 ) side by side, as shown in Figure 1. The friction coefficient between the ground and the concrete blocks is f = 0.3, and the density of the mud is about 1800 kg/m3 . There is concern that the concrete blocks may slide or tip over the lower left edge as the mud level rises.

a) Determine the minimum width w of the concrete blocks at which the blocks will overcome friction and start sliding. Plot the results over the mud height ranging from zero to the top of the retaining wall in 0.2 m-increments.

b) Determine the minimum width w of the concrete blocks at which the blocks will tip over. Plot the results over the mud height ranging from zero to the top of the retaining wall in 0.2 m-increments in the same graph as a).

c) Briefly comment on the results.

On level ground a shell is fired with an initial velocity of 36.0 m/s at 58.0 ∘ above the horizontal and feels no appreciable air resistance. ((INCLUDE ALL ANSWER WITH THE UNITS LIKE m/s OR WHATEVER)) THANK YOU

A) Find the horizontal and vertical components of the shell's initial velocity.

B) How long does it take the shell to reach its highest point?

C) Find its maximum height above the ground.

D) How far from its firing point does the shell land?

E) At its highest point, find the horizontal and vertical components of its acceleration.

F) At its highest point, find the horizontal and vertical components of its velocity.

Use your own words to answer the following questions. Please no handwriting.

Determine what conditions should be considered when implementing passive vs. active cooling techniques.

Describe the advantages of absorption cooling that occurs in a solar cooling system.

Describe two equipment requirements and limitations that must be considered in the analysis and design of solar powered absorption systems.

What are the disadvantages of desiccant solar cooling systems?

Industrial espionage on a distance planet (temperature and atmosphere is unknown) provides the information that successive resonances in a pipe are 210 and 294 Hz. The pipe is 5 m long, but it’s not known whether or not the pipe is open at both ends or only at one end. What is the pipe’s fundamental resonance frequency? The answer is 42Hz