Please show all work and assumptions made, and if possible explain your thoughts. Thank you!

1. How many human “radiators” are required to produce the same power as the world average of 20 Terawatts ? Assume 2000 Calorie per day diets! Answer is 210 billion but I dont know how to get it

2. What conclusion(s) can you draw from your answer to the previous problem?   
   hint: how does this value compare to the power radiated by all people on earth assuming that each person eats 2000 Calories per day?

A laser beam strikes one end of a slab of material, as in the figure below. The index of refraction of the slab is 1.64. (Assume θ = 46.0

Conceptual Work and Kinetic Energy

For each of the following statements, determine whether it is true or false.
1.)True/False  The spring force is a non-conservative force.
2.)True/False  The kinetic energy of an object does not depend on the reference frame of the observer.
3.)True/False  Spring B is stiffer than A (kA<kB). A person must do more work on the block connected to spring A if both springs are ideal and the blocks are pulled by the same amount.
4.)True/False  If the Moon revolves around Earth in a perfectly circular orbit, then Earth does do work on the Moon.
5.)True/False  Work cannot be done in the absence of motion.
6.)True/False  The kinetic energy can be negative.
7.)True/False  The work a person must do to raise a box onto a platform depends on how fast it is raised.
8.)True/False  The kinetic energy of an object depends on the direction of the motion involved.

I still got 4 more attempts left so please answer carefully.

8. How do people take advantage of thermal expansion for practical purposes? How can thermal expansion cause problems for people?

10. A sealed jar contains only air at room temperature and atmospheric pressure. To what temperature must the air be heated in order for its pressure to double? Give a number, and include units.

Can you confirm, within measurement errors, that the period is proportional to the square root of the length ` of pendulum, and that it is independent of the mass m of the bob? Explain what frequency and period mean in your own words. Also, think about conservation of mechanical energy during the oscillation: when is the kinetic energy maximal, when is it minimum? How about the potential energy? Explain how “conservation of mechanical energy” is manifest in oscillation of simple pendulum.

1. A vertical spring has a spring constant of 2500 N/m. A ball with a mass of 0.25 kg is on top of the spring. Use energy conservation to answer the following questions. Sketch the situation for each part.

A. If the spring is compressed 8.3 cm how much energy is stored in the spring?

B. When you release the spring, it pushes the ball upward. What is the speed of the ball at the instant it leaves the spring? The spring is at its relaxed length at this point.

C. How far above the spring will the ball rise before it stops going up?

The tires of a car make 78 revolutions as the car reduces its speed uniformly from 91.0km/h to 63.0km/h . The tires have a diameter of 0.88m .
Part A

What was the angular acceleration of the tires?

Express your answer using two significant figures.

Part B

If the car continues to decelerate at this rate, how much more time is required for it to stop?

Express your answer to two significant figures and include the appropriate units.

Part C

How far does the car go? Find the total distance.

Express your answer to three significant figures and include the appropriate units.

1) The 3rd bright fringe of a double slit interference pattern is 30.0 cm above the central bright fringe. If the angle from the horizontal to this 3rd bright fringe is 12.0 degrees, what is the distance (in meters) between the double slits and the viewing screen?

2) A 500 nm laser illuminates a double slit apparatus with a slit separation distance of 7.73 μm. What is the angle (in degrees) from the horizontal to the 4th bright fringe?

3)A 680 nm laser illuminates a double slit apparatus with a slit separation distance of 7.83 μm. On the viewing screen, you measure the distance from the central bright fringe to the 2nd bright fringe to be 88.2 cm. How far away (in meters) is the viewing screen from the double slits?  

4) A 600 nm laser illuminates a double slit apparatus with a slit separation distance of 3.55 μm. The viewing screen is 1.50 meters behind the double slits. What is the distance (in meters) from the central bright fringe to the 3nd dark fringe?

5) A 600 nm laser illuminates a double slit apparatus with a slit separation distance of 3.55 μm. The viewing screen is 1.50 meters behind the double slits. What is the distance (in cm) between the 2nd and 3rd dark fringes?

A solar cell generates a potential difference of 0.320 V when a 445.0 ? resistor is connected across it and a potential difference of 0.504 V when a 945.0 ? resistor is substituted.

A) What is the internal resistance of the cell in Ohms?

B) What is the emf of the cell?

C) The area of the cell is 27.0 cm² and the rate per unit area at which it receives light energy is 58.0 mW/ cm². What is the efficiency of the cell for converting light energy to thermal energy in the 945.0 ? external resistor?

A ceiling fan consists of a small cylindrical disk with 5 thin rods coming from the center. The disk has mass md = 3.1 kg and radius R = 0.24 m. The rods each have mass mr = 1.3 kg and length L = 0.75 m.

1) SOLVED ALREADY BACKGROUND INFO

moment of inertia of each rod about the axis of rotation = .24kg-m²

^{2) SOLVED ALREADY BACKGROUND INFO} moment of inertia of the disk about the axis of rotation = .09kg-m²

What is the moment of inertia of each rod about the axis of rotation

3) What is the moment of inertia of the whole ceiling fan?

4) When the fan is turned on, it takes t = 3.1 s and a total of 12 revolutions to accelerate up to its full speed. What is the magnitude of the angular acceleration?

5) What is the final angular speed of the fan?

When the electricity goes out on your campus, a backup source powers the servers that handle communications and the internet. Rather than use batteries, many installations use a flywheel, a heavy rotating disk that spins, very rapidly with nearly zero friction. An electric motor spins up the flywheel, which continues to spin with very little energy input. When the ststem needs to provide power, the flywheel's motion is used to turn an electric generator. A typical system has a 540 kg cylinder with a radius of 0.30 m. A small electric motor provides a constant 2.8 N-m torque to spin up the cylinder. A) Calculate the frequency for cylinder s motion? B) Calculate angular speed in rad/s? C)Calculate moment of inertia of the cylinder? D) Calculate the angular acceleration?

1. Consider the following nuclides:

                                          NUCLIDE                             MASS (amu)

                                                  ₅¹¹B 11.009305

                                                ₆¹²C 12.0000

₄₂¹⁰⁰Mo 99.90747

                                                ₈₃²⁰⁹ Bi 208.97973

                                                ₉₂²³⁸ U 238.050

For each of these nuclides, find (a) the binding mass in atomic mass units and (b) the binding energy in Mev.

2. (a) Find the average binding energy per nucleon of each nuclide listed in problem 1, and (b) mark the location of each nuclide on the attached graph of average binding energy per nucleon versus atomic mass number.

3. Find the average radius of each nuclide, listed in problem 1.

A pendulum of length l with a ball of mass m is raised 90◦ clockwise from its hanging position and released. A block of mass 2m rests on a frictionless surface at the pendulum’s hanging position so that it is struck just as the pendulum reaches its lowest point. The two objects collide elastically and the pendulum rebounds, swinging back up to an angle θ clockwise from the vertical. What is the angle θ, and what is the speed of the block after the collision?

An empty parallel plate capacitor is connected between the terminals of a 10.7-V battery and charged up. The capacitor is then disconnected from the battery, and the spacing between the capacitor plates is doubled. As a result of this change, what is the new voltage between the plates of the capacitor?