How much work, in Joules, does it take to dig up a cylindrically shaped hole of depth 2 meters and outer diameter 3 meters? How many servings of pasta are required to complete this work, assuming the energy from the pasta is converted with 5% efficiency to work? Assume that one serving of pasta contains 200 Cal, and the density of soil is 1,200 kg/m3.

1. Why are the thermal detectors slower and less sensitive than the photon detectors?

2. What are the physical origins of the shot noise and Johnson noise in an optical detector?

Stars fuse lighter nuclei to form heavier nuclei (to the extent that they are capable and the fusion process is energetically favorable). Based on the plot of binding energy per nucleon, do you expect to see fusion of uranium atoms in a star? Why/why not?

Suppose two worlds, each having mass M and radius R, coalesce into a single world. Due to gravitational contraction, the combined world has a radius of only 7/8 R. What is the average density of the combined world as a multiple of ρ0, the average density of the original two worlds?

Two copper plates 0.50cm thick have a 0.10mm sheet of glass sandwiched between them. One copper plate is kept in contact with flowing ice water and the other is in contact with stream. What are the temperatures of the two copper-glass interfaces, and what is the power transferred through a 10cm by 10cm area? kcopper=385 K/mC and kglass=0.8 K/mC

The answers given are: 9C, 91 C, and 6.6E3 W. I am just trying to learn the process of solving problems like this and my closest answer was 7837 W, which is still off.

Given the following factors below, describe how the molecules of the reactants are being affected. Give examples.

1. Reactant concentration

2. Increase in temperature


3. Increase in surface area of the solid reactants.

4. Properly Oriented molecules

A reaction is endothermic. Is the energy of the product higher or lower than the energy of the
reactants? Explain your answer.

A rotating wheel requires 2.97-s to rotate through 37.0 revolutions. Its angular speed at the end of the 2.97-s interval is 97.0 rad/s. What is the constant angular acceleration of the wheel? _____ rad/s2

A 45.3-cm diameter disk rotates with a constant angular acceleration of 2.30 rad/s². It starts from rest at t = 0, and a line drawn from the center of the disk to a point P on the rim of the disk makes an angle of 57.3° with the positive x-axis at this time.

(a) Find the angular speed of the wheel at t = 2.30 s

5.26 (correct) rad/s

(b) Find the linear velocity and tangential acceleration of P at t = 2.30 s.

linear velocity- ? m/s

tangential acceleration- ? m/s²

(c) Find the position of P (in degrees, with respect to the positive x-axis) at t = 2.30s.

^? °

A planet of mass 6 × 10²⁵ kg is in a circular orbit of radius 4 × 10¹¹ m around a star. The star exerts a force on the planet of constant magnitude 1.8 × 10²³ N. The speed of the planet is 3.4 × 10⁴ m/s.
(a) In half a "year" the planet goes half way around the star. What is the distance that the planet travels along the semicircle?

(b) During this half "year", how much work is done on the planet by the gravitational force acting on the planet?

(c) What is the change in kinetic energy of the planet?

(d) What is the magnitude of the change of momentum of the planet?

Starting from the 2D time-independent Schr ̈odinger Equation, and using your knowledge

of the 1D harmonic oscillator, write down the normalized ground-state and the first

excited state, with both position and time dependence included. Come up with a way

of writing these states in shorthand using kets.

Three infinite straight wires are fixed in place and aligned parallel to the z-axis as shown. The wire at (x,y) = (-13.5 cm, 0) carries current I₁ = 3.2 A in the negative z-direction. The wire at (x,y) = (13.5 cm, 0) carries current I₂ = 1.4 A in the positive z-direction. The wire at (x,y) = (0, 23.4 cm) carries current I₃ = 5.1 A in the positive z-direction.

1)

What is B_x(0,0), the x-component of the magnetic field produced by these three wires at the origin?T

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2)

What is B_y(0,0), the y-component of the magnetic field produced by these three wires at the origin?T

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3)

What is F_x(1), the x-component of the force exerted on a one meter length of the wire carrying current I₁?N

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4)

What is F_y(1), the y-component of the force exerted on a one meter length of the wire carrying current I₁?N

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5)

What is F_x(2), the x-component of the force exerted on a one meter length of the wire carrying current I₂?

a) Determine the mass of water vapor, initially at 130 ° C, needed to heat 200 g of distilled water in a 100 g glass container, to go from 20 ° C to 50 ° C.

The specific heat of water vapor is 2.01x103 J / kg ° C, the specific heat of distilled water is 4.19x103 J / kg ° C, the latent heat of condensation of water vapor is 2.26x106 J / kg and the Specific heat of the glass is 837 J / kg ° C

Derive the expression for the time averaged heating in the metal in which AC current of frequency ω flows – use the expression for the AC conductivity and P= ⋅EJ relation for instant power

Draw an experimental setup in the Laboratory in which you are working, where only interference is observed. Explain why you use each element you use in the setup.