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Questions (293)

A 4-point bending test is performed on the same beam, with symmetric loads of 5kN separated by 2m.Draw the bending moment and
1. 0 answers
2. 676 views
A 3-point bending test is performed on a simply supported beam of length L=4m and of rectangular cross-section, with width b and
1. 1 answer
2. 1,091 views
Calculate the ratio of the moments of inertia I1I2 of two beams of rectangular cross section of the same width, one with a
1. 1 answer
2. 943 views
A 3m long balance beam is simply supported with an overhang at each end of a=0.5m. A gymnast weighing 50kg is standing a
1. 0 answers
2. 612 views
A thin-wall cylindrical tank has radius R, wall thickness t≪R and is subjected to an internal pressure p. The cylindrical wall
1. 0 answers
2. 737 views
At a point in a plate subjected to plane stress loading along its surface, the cartesian stress components acting on the x-face
1. 0 answers
2. 641 views
In this problem, you will construct the 2D Mohr's circle for two plane stress states defined in terms of the Cartesian
1. 0 answers
2. 566 views
A compression bar, having a square cross section of side length b, must support a compressive load of magnitude W, uniformly
1. 0 answers
2. 1,095 views
Arrange the following functions in increasing order of growth rate (with g(n) following f(n) in your list if and only if
1. 0 answers
2. 637 views
Consider the "Hybrid Model" described in lecture 3.4, with m=10. Let us compare the cases of a=0.8 and a=0.2.At date t=10,000,
1. 0 answers
2. 490 views
Consider the "Preferential Attachment Model" described in lecture 3.3, with m=10.At date t=40, what are: (1) the expected degree
1. 1 answer
2. 521 views
Consider the model of "Growing Random Networks" described in lecture 3.1 (so the first model where links are added to existing
1. 2 answers
2. 553 views
Which of the following processes is used in order to fabricate monocrystalline silicon?Note that more than one correct answer is
1. 0 answers
2. 853 views
The width of the space charge region at a p-n junction is reduced by applying a voltage bias over the p-n junction. What is the
1. 1 answer
2. 690 views
Consider a propositional language with three propositional constants - mushroom, purple, and poisonous - each indicating the
1. 3 answers
2. 3,067 views
Suppose ABC is a frequent itemset and BCDE is NOT a frequent itemset. Given this information, we can be sure that certain other
1. 0 answers
2. 1,026 views
Imagine there are 100 baskets, numbered 1,2,...,100, and 100 items, similarly numbered. Item i is in basket j if and only if i
1. 1 answer
2. 1,284 views
Suppose we want to assign points to whichever of the points (0,0) or (100,40) is nearer. Depending on whether we use the L1 or
1. 1 answer
2. 542 views
The edit distance is the minimum number of character insertions and character deletions required to turn one string into
1. 4 answers
2. 769 views
Suppose our input data to a map-reduce operation consists of integer values (the keys are not important). The map function takes
1. 3 answers
2. 2,232 views
Let's assume that solar light reaches a silicon solar cell with an angle of incidence of θi=0o. For simplicity, let's consider
1. 0 answers
2. 688 views
A solar cell with dimensions 12cm x 12cm is illuminated at standard test conditions. The cell presents the following external
1. 1 answer
2. 602 views
The current density of an ideal p-n junction under illumination can be described by:J(V)=Jph−J0(e^qV/kT−1) where Jph is the
1. 1 answer
2. 863 views
The width of the space charge region at a p-n junction is reduced by applying a voltage bias over the p-n junction. What is the
1. 0 answers
2. 533 views
A cube of the isotropic, linear elastic epoxy resin E=2GPa, ν=0.3, α=50×10−6K−1 at 20∘C is unloaded. It is then heated
1. 5 answers
2. 1,512 views
An isotropic epoxy resin (E=2GPa, ν=0.3) is reinforced by unidirectional glass fibers (Eglass=70GPa), aligned in the 2
1. 3 answers
2. 952 views
A linear elastic, isotropic epoxy resin with elastic modulus, E=2GPa, and Poisson’s ratio, ν=0.3, is loaded by the following
1. 2 answers
2. 1,506 views
Rubber particles, roughly 1mm in diameter, have been added to an epoxy resin to increase its resistance to crack growth.
1. 1 answer
2. 1,224 views
Aluminum is a cubic crystal, withS11=1.59×10−11 m2/N S12=−0.58×10−11 m2/N S44=3.52×10−11 m2/N What are the Young's
1. 4 answers
2. 1,320 views
A cylindrical pressure vessel, with a diameter of 40cm and a wall thickness of 10mm is made of steel (isotropic, with Young’s
1. 6 answers
2. 1,631 views
The molar crosslink density of a rubber is measured to be 468mol/m3 for a temperature T=300K.What is the Young's modulus of the
1. 2 answers
2. 2,457 views
Imagine a container is removed from a hot oven and plunged into cold water. Use your answer from Question 3 to justify which
1. 1 answer
2. 858 views
A steel bar of length L and cross-sectional area A is fitted between rigid supports.Write an expression for the stress in the
1. 1 answer
2. 1,027 views
Given an aluminum shell perfectly bonded to a steel core, what is the thermal stress in the aluminum shell when the system is
1. 2 answers
2. 1,545 views
The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^nDerive and expression for the stiffness
1. 1 answer
2. 609 views
The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^nDerive an expression for the equilibrium
1. 0 answers
2. 523 views
Rubber particles are sometimes dispersed in an epoxy matrix to increase its resistance to the propagartion of cracks. Rubber has
1. 0 answers
2. 484 views
A unidriectional, continuously reinforced glass fiber composite has Vf=60 volume percent fibers in a matrix of epoxy. Glass has
1. 3 answers
2. 989 views
The boron fibers are produced by chemical vapor deposition of boron onto fine tungsten wires of dW=10μm. The final wire
1. 2 answers
2. 1,141 views
Consider a room that is 6m long, 5m wide and 3m high and whose walls, floor and ceiling have the same sound absorption
1. 0 answers
2. 670 views
How would you expect the directivity of the piston to vary as the temperature of air decreases? (Hint: Low temperature ->
1. 0 answers
2. 472 views
A breathing sphere of radius 0.1m radiates spherical waves into air at 100Hz with an intensity of 200mW/m2 at the distance 0.5m
1. 0 answers
2. 592 views
List one of the vocal technology topics and describe how it has changed and/or affected popular music.1. Time Based Effects
1. 0 answers
2. 566 views
The current peak wavelength of the CMB corresponds to a blackbody of temperature 2.74K. What was the peak wavelength of the CMB
1. 2 answers
2. 2,890 views
What about a for a supernova in an elliptical galaxy of 10^12 solar masses and radius of 50 kpc?Yes or No
1. 0 answers
2. 418 views
Supernovae can eject material at velocities of 0.001c. Will gas ejected by a supernova which occurs inside a dwarf galaxy with a
1. 0 answers
2. 725 views
The star Polaris has a surface temperature of roughly 6500 K and a radius of approximately 50 solar radii. Find the luminosity
1. 1 answer
2. 2,618 views
A galaxy is receding away from us with a recession velocity of 100,000 km/s. What is the distance to this galaxy? What is the
1. 1 answer
2. 1,038 views
A quasar is observed at a redshift of z=1, which corresponds to a comoving radial distance of 3 Gpc. Its observed bolometric
1. 2 answers
2. 2,934 views
A dedicated professor has been holding infinitely long office hours. Undergraduate students arrive according to a Poisson
1. 2 answers
2. 781 views
Uncle Henry has been having trouble keeping his weight constant. In fact, during each week, his weight changes from the
1. 1 answer
2. 804 views
Suppose that you move to a new house and you are 10% sure that your new house's phone number is 561290. To verify this, you use
1. 2 answers
2. 800 views
Imagine that you have found an object out in space. When you use the inverse square law to compute its luminosity, you get a
1. 3 answers
2. 1,353 views
Imagine that you are an astronomer, and you are planning to do a survey to find new brown-dwarf stars. You need to calculate how
1. 2 answers
2. 1,243 views
Imagine that you are a particle physicist, and you have come up with a theory that some gamma-ray bursts come from the decay of
1. 1 answer
2. 718 views
The luminosity of the Sun is 4*10^33 erg/s, and its radius is 7*10^10 cm.What is the Sun's effective temperature? Please enter
1. 3 answers
2. 965 views
Imagine you are in a spaceship one million km from a black hole of mass kg. Initially you are flying directly away from it at a
1. 2 answers
2. 482 views
The luminosity of the Sun is 4*10^33 erg/s, and its radius is 7*10^10 cm.What is the Sun's effective temperature? Please enter
1. 0 answers
2. 1,054 views
Choose one answer for each questionHow old is the universe? 6,000 years old 380,000 years old 13.8 billion years old 13.8
1. 3 answers
2. 686 views
We are given the following statistics about the number of children in the families of a small village.There are 100 families: 10
1. 1 answer
2. 1,270 views
All ships travel at the same speed through a wide canal. Each ship takes days to traverse the length of the canal. Eastbound
1. 1 answer
2. 6,690 views
In parts 1, 3, 4, and 5 below, your answers will be algebraic expressions. Enter 'lambda' for and 'mu' for . Follow standard
1. 4 answers
2. 7,135 views
Fred is giving away samples of dog food. He makes visits door to door, but he gives a sample away (one can of dog food) only on
1. 0 answers
2. 635 views
Another possible energy source would be gravity. Imagine that the strange object contains a black hole of mass mbh. You drop a
1. 0 answers
2. 629 views
One possible energy source for the mysterious object you've just discovered is the fusion of hydrogen to form carbon-12 (the
1. 1 answer
2. 760 views
Imagine that a rival astronomer proposes that your mysterious object is actually the mouth of a wormhole to another dimension.
1. 1 answer
2. 908 views
Imagine that you have just discovered a strange object. This object is a distance D away, has a redshift z, and you measure a
1. 0 answers
2. 565 views
For any given flight, an airline tries to sell as many tickets as possible. Suppose that on average, 10% of ticket holders fail
1. 3 answers
2. 1,519 views
A roughly spherical asteroid with a diameter of 1 km, and a mean density of 4 g/cm^3, hits the Earth with a relative speed 1.5
1. 8 answers
2. 6,076 views
Let X be a continuous random variable. We know that it takes values between 0 and 3 , but we do not know its distribution or its
1. 3 answers
2. 963 views
The random variables X1,..,Xn are independent Poisson random variables with a common parameter Lambda . Find the maximum
1. 1 answer
2. 1,463 views
For any given flight, an airline tries to sell as many tickets as possible. Suppose that on average, 10% of ticket holders fail
1. 0 answers
2. 1,134 views
Let Sn be the number of successes in n independent Bernoulli trials, where the probability of success for each trial is 1/2 .
1. 3 answers
2. 1,362 views
In the past few million years of Mars the main source of climate variation has been the slow escape of the atmosphere.Probably
1. 1 answer
2. 605 views
Sometimes a crater from the Noachian period can be found inside of a crater from the Amazonian period.Probably true Maybe
1. 1 answer
2. 699 views
The northern plains of Mars have many characteristics that you would expect from their being an ancient ocean floor.Probably
1. 1 answer
2. 807 views
Rain was once common on Mars.Probably true Maybe/unclear Probably false
1. 1 answer
2. 406 views
Rank the following hypothetical planets -- all of which have the same total mass and same radius -- from lowest moment of
1. 3 answers
2. 1,213 views
Which of the following statements is correct? (check all that apply)If liquid water is not stable on the surface of Mars, liquid
1. 0 answers
2. 951 views
Random variables X and Y are distributed according to the joint PDFfX,Y(x,y) = {ax,0,if 1≤x≤2 and 0≤y≤x,otherwise.} 1.
1. 1 answer
2. 2,508 views
Let X and Y be normal random variables with means 0 and 2, respectively, and variances 1 and 9, respectively. Find the
1. 1 answer
2. 760 views
Consider the following joint PMF of the random variables X and Y:pX,Y(x,y)={1/72⋅(x2+y2),if x∈{1,2,4} and y∈{1,3}, 0,
1. 5 answers
2. 971 views
We start with a collection of n (distinguishable) individuals whom we want to split into three possible teams: the blue team,
1. 6 answers
2. 679 views
To get a complete collection of stamps, Ann needs to have 5 specific (and different) kinds of stamps, denoted by k1,…,k5. She
1. 4 answers
2. 649 views
Alice has five coins in a bag: two coins are normal (i.e., fair with one face Heads and the other face Tails), two are
1. 7 answers
2. 1,404 views
Is there a correlation between the average number of books a person reads per month and their level of intelligence?
1. 0 answers
2. 4,771 views
What is the estimated total lifetime for a star with mass 0.7 Msun ? (in billions of year)
1. 0 answers
2. 672 views
The coolest star whose peak blackbody wavelength can be observed with the human eye (the exact range of visible light varies
1. 1 answer
2. 1,100 views
How close to the sun Ganymede would have to be in order to hold water in its atmosphere. (in AU)
1. 0 answers
2. 429 views
A newly discovered planet has a surface temperature of 330 K and a density of 6 g/cm3. What minimum radius does the planet need
1. 1 answer
2. 788 views
Imagine you are on some far away planetary system looking for planets in the galactic neighborhood and you spot our sun in your
1. 1 answer
2. 516 views
Consider 10 independent tosses of a biased coin with the probability of Heads at each toss equal to p , where 0 < p < 1 .1. Let
1. 1 answer
2. 1,903 views
You are given the set of letters ( A, B, C, D, E ). What is the probability that in a random five-letter string (in which each
1. 3 answers
2. 5,245 views
The newest invention is a three-sided die. On any roll of this die, the result is 1 with probability 1/2, 2 with probability
1. 2 answers
2. 4,119 views
A group of 90 students is to be split at random into 3 classes of equal size. All partitions are equally likely. Joe and Jane
1. 2 answers
2. 785 views
A player is randomly dealt a sequence of 13 cards from a standard 52-card deck. All sequences of 13 cards are equally likely. In
1. 2 answers
2. 1,562 views
Alice plays the following game with Bob. First, Alice randomly chooses a set of 4 cards out of a 52-card deck, memorizes them,
1. 1 answer
2. 1,524 views
The following questions concern the iconic Nestle Toll House Chocolate Chip Cookie recipe, shown below:2 1/4 cups all-purpose
1. 5 answers
2. 2,812 views
The following questions concern the iconic Nestle Toll House Chocolate Chip Cookie recipe, shown below:2 1/4 cups all-purpose
1. 2 answers
2. 1,484 views
1)Buttermilk has 9 grams of protein and 12 grams of carbohydrate per cup (237ml). Estimate the concentration in mol/L of protein
1. 9 answers
2. 3,722 views

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