Blog

What are the two dimensions (rows and columns) of the utility matrix in recommendation systems?

A measurement of an electron’s speed is 2.5 × 106 m/s and has an uncertainty of 15%. What is the minimum uncertainty in its position? (h = 6.626 × 10-34 J·s, mel = 9.11 × 10-31 kg)

The figure (not to scale) shows a pV diagram for 4.6 g of helium gas (He) that undergoes the process 1 → 2 → 3. Find the value of V3. The ideal gas constant is R = 8.314 J/(mol·K) = 0.0821 L·atm/(mol·K), and the atomic weight of helium is 4.0 g/mol.  

The energy of the ground state in the Bohr model of the hydrogen atom is -13.6 eV. The energy of the n = 3 state of hydrogen in this model is closest to

A 3.2-L volume of neon gas (Ne) is at a pressure of 4.7 atm and a temperature of 400 K. The atomic mass of neon is 20.2 g/mol, Avogadro’s number is 6.022×1023 molecules/mol, and the ideal gas constant is R= 8.314 J/(mol·K) = 0.0821 L·atm/(mol·K). The mass of the neon gas is closest to

Two sources of light illuminate a double slit simultaneously. One has a wavelength of 700 nm and the second has an unknown wavelength. The m = 5 bright fringe of the unknown wavelength overlaps the m = 4 bright fringe of the light of 700 nm wavelength. What is the unknown wavelength?

A metal having a work function of 1 eV is illuminated with monochromatic light whose photon energy is 3.5 eV. What is the maximum kinetic energy of the photoelectrons produced by this light? (h = 6.626 × 10-34 J · s, 1 eV = 1.60 × 10-19 J)

The figure (not to scale) shows a pV diagram for 6.9 g of helium gas (He) that undergoes the process 1 → 2 → 3. Find the value of V3. The ideal gas constant is R = 8.314 J/(mol·K) = 0.0821 L·atm/(mol·K), and the atomic weight of helium is 4.0 g/mol.  

Programming Consider the task of checking to see if a graph contains a cycle. This task can, of course, be accomplished with a recursive DFS algorithm. Unfortunately, in very large graphs it is not appropriate to use recursion to explore, because it requires a vast amount of system memory (to track each recursive call). Implement a method for checking for a cycle in a graph using the DFS algorithm WITHOUT using recursion. Assume that the Stack ADT is available and you are using the standard Graph ADT discussed in class. (Huge Hint: start by thinking about BFS, and how it works without recursion.)   Assume a marked variable exists and has been set up to be the size of the graph and with every index set to false. public static boolean[] marked;public static boolean hasCycle(Graph G, int start) { Stack s = new Stack(); //TODO: implement this method.

At absolute temperature T, a black body radiates its peak intensity at wavelength λ. At absolute temperature 2T, what would be the wavelength of the peak intensity?