Questions LLC
Login
or
Sign Up
Ask a New Question
qwerty
Questions and answers by
qwerty
, page 2
Questions (293)
How the asymmetry between matter
and anti-matter in our Universe might be generated. Why might neutrinos be a key player in
3 answers
546 views
Basically the ``Bohr radius'' for the dark matter is
rB=ℏ^2 / GN M m^2 where m is the dark matter mass, M is the total amount
1 answer
429 views
Which nutrient is most abundant (by weight) in eggplants?
Carbohydrates Fats Proteins Add up the total mass of carbohydrates,
4 answers
898 views
Identify the major macronutrient by weight in each of the following key ingredients.
Olive oil Carbohydrates Fats Proteins
1 answer
488 views
1)Buttermilk has 9 grams of protein and 12 grams of carbohydrate per cup (237ml). Estimate the concentration in mol/L of protein
10 answers
3,644 views
The following questions concern the iconic Nestle Toll House Chocolate Chip Cookie recipe, shown below:
2 1/4 cups all-purpose
4 answers
1,414 views
The following questions concern the iconic Nestle Toll House Chocolate Chip Cookie recipe, shown below:
2 1/4 cups all-purpose
6 answers
2,736 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,
3 answers
1,452 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
4 answers
1,481 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
3 answers
719 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
4 answers
4,017 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
5 answers
asked by
qwerty
5,072 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
3 answers
1,824 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 answer
436 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
3 answers
706 views
How close to the sun Ganymede would have to be in order to hold water in its atmosphere. (in AU)
1 answer
369 views
The coolest star whose peak blackbody wavelength can be observed with the human eye (the exact range of visible light varies
3 answers
1,027 views
What is the estimated total lifetime for a star with mass 0.7 Msun ? (in billions of year)
1 answer
623 views
Is there a correlation between the average number of books a person reads per month and their level of intelligence?
2 answers
4,698 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
7 answers
1,313 views
To get a complete collection of stamps, Ann needs to have 5 specific (and different) kinds of stamps, denoted by k1,…,k5. She
5 answers
561 views
We start with a collection of n (distinguishable) individuals whom we want to split into three possible teams: the blue team,
7 answers
588 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,
6 answers
878 views
Let X and Y be normal random variables with means 0 and 2, respectively, and variances 1 and 9, respectively. Find the
2 answers
678 views
Random variables X and Y are distributed according to the joint PDF
fX,Y(x,y) = {ax,0,if 1≤x≤2 and 0≤y≤x,otherwise.} 1.
3 answers
2,432 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 answer
863 views
Rank the following hypothetical planets -- all of which have the same total mass and same radius -- from lowest moment of
4 answers
1,126 views
Rain was once common on Mars.
Probably true Maybe/unclear Probably false
1 answer
351 views
The northern plains of Mars have many characteristics that you would expect from their being an ancient ocean floor.
Probably
4 answers
701 views
Let Sn be the number of successes in n independent Bernoulli trials, where the probability of success for each trial is 1/2 .
4 answers
1,267 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 answer
1,067 views
The random variables X1,..,Xn are independent Poisson random variables with a common parameter Lambda . Find the maximum
3 answers
1,382 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
4 answers
880 views
For any given flight, an airline tries to sell as many tickets as possible. Suppose that on average, 10% of ticket holders fail
4 answers
1,428 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 answer
503 views
Imagine that a rival astronomer proposes that your mysterious object is actually the mouth of a wormhole to another dimension.
3 answers
827 views
One possible energy source for the mysterious object you've just discovered is the fusion of hydrogen to form carbon-12 (the
2 answers
690 views
Another possible energy source would be gravity. Imagine that the strange object contains a black hole of mass mbh. You drop a
2 answers
586 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 answer
572 views
In parts 1, 3, 4, and 5 below, your answers will be algebraic expressions. Enter 'lambda' for and 'mu' for . Follow standard
6 answers
asked by
qwerty
6,987 views
We are given the following statistics about the number of children in the families of a small village.
There are 100 families: 10
3 answers
1,172 views
Choose one answer for each question
How old is the universe? 6,000 years old 380,000 years old 13.8 billion years old 13.8
4 answers
628 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 answer
987 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
3 answers
433 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
4 answers
881 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
3 answers
655 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
4 answers
1,174 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
5 answers
1,256 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
3 answers
721 views
Uncle Henry has been having trouble keeping his weight constant. In fact, during each week, his weight changes from the
2 answers
746 views
A dedicated professor has been holding infinitely long office hours. Undergraduate students arrive according to a Poisson
3 answers
691 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
2 answers
941 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 answer
365 views
List one of the vocal technology topics and describe how it has changed and/or affected popular music.
1. Time Based Effects
1 answer
487 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
2 answers
543 views
How would you expect the directivity of the piston to vary as the temperature of air decreases? (Hint: Low temperature ->
1 answer
427 views
Consider a room that is 6m long, 5m wide and 3m high and whose walls, floor and ceiling have the same sound absorption
2 answers
599 views
The boron fibers are produced by chemical vapor deposition of boron onto fine tungsten wires of dW=10μm. The final wire
3 answers
1,047 views
A unidriectional, continuously reinforced glass fiber composite has Vf=60 volume percent fibers in a matrix of epoxy. Glass has
4 answers
916 views
Rubber particles are sometimes dispersed in an epoxy matrix to increase its resistance to the propagartion of cracks. Rubber has
1 answer
429 views
The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^n
Derive an expression for the equilibrium
1 answer
458 views
The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^n
Derive and expression for the stiffness
2 answers
546 views
Given an aluminum shell perfectly bonded to a steel core, what is the thermal stress in the aluminum shell when the system is
4 answers
1,471 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
2 answers
969 views
Imagine a container is removed from a hot oven and plunged into cold water. Use your answer from Question 3 to justify which
2 answers
804 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
5 answers
2,324 views
A cylindrical pressure vessel, with a diameter of 40cm and a wall thickness of 10mm is made of steel (isotropic, with Young’s
7 answers
1,559 views
Aluminum is a cubic crystal, with
S11=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
5 answers
1,226 views
Rubber particles, roughly 1mm in diameter, have been added to an epoxy resin to increase its resistance to crack growth.
2 answers
1,161 views
A linear elastic, isotropic epoxy resin with elastic modulus, E=2GPa, and Poisson’s ratio, ν=0.3, is loaded by the following
4 answers
1,432 views
An isotropic epoxy resin (E=2GPa, ν=0.3) is reinforced by unidirectional glass fibers (Eglass=70GPa), aligned in the 2
4 answers
889 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
6 answers
1,413 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 answer
477 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
2 answers
806 views
A solar cell with dimensions 12cm x 12cm is illuminated at standard test conditions. The cell presents the following external
2 answers
532 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 answer
631 views
Suppose our input data to a map-reduce operation consists of integer values (the keys are not important). The map function takes
4 answers
2,165 views
The edit distance is the minimum number of character insertions and character deletions required to turn one string into
5 answers
694 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
2 answers
495 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
2 answers
1,232 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 answer
965 views
Consider a propositional language with three propositional constants - mushroom, purple, and poisonous - each indicating the
4 answers
2,991 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
2 answers
606 views
Which of the following processes is used in order to fabricate monocrystalline silicon?
Note that more than one correct answer is
1 answer
790 views
Consider the model of "Growing Random Networks" described in lecture 3.1 (so the first model where links are added to existing
3 answers
512 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 answer
475 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 answer
440 views
Arrange the following functions in increasing order of growth rate (with g(n) following f(n) in your list if and only if
2 answers
589 views
A compression bar, having a square cross section of side length b, must support a compressive load of magnitude W, uniformly
1 answer
1,011 views
In this problem, you will construct the 2D Mohr's circle for two plane stress states defined in terms of the Cartesian
3 answers
499 views
At a point in a plate subjected to plane stress loading along its surface, the cartesian stress components acting on the x-face
2 answers
581 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 answer
666 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
2 answers
539 views
Calculate the ratio of the moments of inertia I1I2 of two beams of rectangular cross section of the same width, one with a
2 answers
889 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
2 answers
1,009 views
A 4-point bending test is performed on the same beam, with symmetric loads of 5kN separated by 2m.
Draw the bending moment and
2 answers
617 views
A hollow cylinder with outer radius r0 and inner radius ri is loaded by a uniformly distributed load q across its length L. The
2 answers
1,357 views
A cantilever beam, made of a material with a Young's modulus, E with a rectangular cross section with a moment of inertia I, is
4 answers
1,160 views
A rectangular beam, with cross-sectional width b, height h, Young's modulus Erect, has the same flexural rigidity as a circular
3 answers
1,517 views
Calculate the deflection v at the free end, B, for the beams shown below. Both beams have the same rectangular cross section.
2 answers
539 views
Pages
1
2
3
