Given the complex number z = 1 + i*sqrt(3), what is the trigonometric (polar) form of z?
Mathematics
Question · Easy
What is the value of the complex expression (1 + i)^8?
Question · Medium
In the complex plane, what is the geometric locus of points M representing complex numbers z such that |z - 2 + 3i| = 5?
For a real constant a, lim_{x->0} (e^(ax) - 1) / x = 6. What is a?
What is the derivative of the function f(x) = ln(x^2 + 1) for all real x?
What is the general solution of the differential equation y' - 3y = 0 on R?
What is the particular solution to the differential equation y'' + 4y = 0 satisfying y(0) = 1 and y'(0) = 2?
Question · Hard
Evaluate the definite integral I = int_0^1 (2x + 1) * e^(x^2 + x) dx.
Using integration by parts, evaluate J = int_1^e x * ln(x) dx.
What is the remainder of 3^100 when divided by 7?
Using the Euclidean algorithm, what is the greatest common divisor (GCD) of 348 and 124?
According to Bezout's theorem, two integers a and b are coprime if and only if there exist integers u and v such that:
In 3-dimensional space, what is the Cartesian equation of the plane P passing through point A(1, -2, 3) with normal vector n(2, 3, -1)?
What is the distance from point M(1, 2, -1) to the plane P with equation 2x - y + 2z - 5 = 0?
What is the dot product (scalar product) of vectors u(1, -3, 2) and v(4, 2, 1) in an orthonormal coordinate system?
A random variable X follows a binomial distribution B(n = 10, p = 0.3). What is the expected value (mean) E(X) and variance V(X)?
An urn contains 5 red balls and 3 green balls. Two balls are drawn simultaneously at random. What is the probability of drawing two balls of different colors?
Given two events A and B such that P(A) = 0.4, P(B) = 0.5, and P(A cap B) = 0.2, what is the conditional probability P(A | B)?
What is the horizontal asymptote of the function f(x) = (3x^2 - 5x + 2) / (x^2 + 4) as x tends to +infinity?
What are the inflection points of the curve representing f(x) = x^3 - 3x^2 + 2?
What is the sum of the infinite geometric series S = 1 + 1/3 + 1/9 + 1/27 + ...?
Let f(x) = ln(x) / x on ]0, +infinity[. What is the coordinates of the absolute maximum of f?
In the set of complex numbers C, what are the solutions to the quadratic equation z^2 - 2z + 5 = 0?
If a sequence (u_n) is defined by u_0 = 2 and u_{n+1} = 3*u_n - 4 for all n >= 0, what is the explicit expression of u_n in terms of n?
What is the value of the limit lim_{x->+infinity} (x - sqrt(x^2 - 4x))?
A projectile is launched from ground level with an initial velocity v_0 = 20 m/s at an angle alpha = 30 degrees above the horizontal. Taking g = 10 m/s^2 and neglecting air resistance, what is the maximum height H reached by the projectile?
Physics
A satellite of mass m describes a uniform circular orbit of radius r around the Earth (mass M_T). Taking G as Newton's universal gravitational constant, what is the orbital speed v of the satellite?
Kepler's third law states that for any planet orbiting the Sun, T^2 / a^3 is constant. What is this constant in terms of the solar mass M_S and gravitational constant G?
A proton with elementary charge q = 1.6 * 10^-19 C enters perpendicularly into a uniform magnetic field B = 0.50 T. If the magnetic force acting on the proton is F = 1.6 * 10^-13 N, what is the speed v of the proton?
An ideal solenoid of length L = 0.50 m has N = 1000 turns and carries a direct current I = 2.0 A. Given mu_0 = 4*pi * 10^-7 T*m/A, what is the magnitude of the magnetic field B inside the solenoid?
A flat circular coil with N = 100 turns and cross-sectional area S = 0.020 m^2 is placed perpendicular to a uniform magnetic field. The magnetic field decreases uniformly from 0.80 T to 0.20 T in Delta t = 0.30 s. What is the induced electromotive force (EMF) magnitude |e| in the coil?
An inductor with self-inductance L = 0.20 H carries an electric current I = 3.0 A. What is the magnetic energy E_m stored in this inductor?
In a series RL circuit subjected to a voltage step, the coil has inductance L = 50 mH and the circuit has total resistance R = 25 ohms. What is the time constant tau of the circuit?
A series RLC circuit comprises a resistor R = 50 ohms, an inductor L = 0.10 H, and a capacitor C = 10 microfarads (10 * 10^-6 F). What is the angular resonance frequency omega_0 of the circuit?
At the resonance frequency omega_0 in a series RLC circuit, what is the value of the total impedance Z of the circuit?
A frictionless horizontal spring-mass system consists of a mass m = 0.25 kg attached to a spring of spring constant k = 100 N/m. What is the natural period of oscillation T_0? (Take pi ≈ 3.14)
A simple pendulum has an oscillation period of T = 2.0 s at a location where g = 9.80 m/s^2. Taking pi^2 ≈ 9.87, what is the length L of the pendulum string?
In a Young's double-slit experiment, monochromatic light of wavelength lambda = 600 nm (6.0 * 10^-7 m) illuminates two slits separated by distance a = 0.30 mm (3.0 * 10^-4 m). The screen is at distance D = 1.5 m. What is the fringe width (interfrange i)?
A light ray in air (n_1 = 1.00) enters a glass prism (n_2 = 1.50) with an angle of incidence i_1 = 30 degrees. According to Snell-Descartes law of refraction, what is sin(i_2)?
According to Einstein's photoelectric equation, what is the maximum kinetic energy E_c,max of photoelectrons emitted from a metal with extraction work function W_0 when illuminated by light of frequency nu?
A radioactive isotope has a half-life of T = 8.0 days. If the initial activity of a sample is A_0 = 1600 Bq, what is its activity after 24 days?
The mass defect Delta m of a helium-4 nucleus (^4_2He) is 0.0304 u. Taking 1 atomic mass unit (u) equivalent to 931.5 MeV/c^2, what is the total binding energy E_l of this nucleus?
During beta-minus (beta-) radioactive decay, an unstable nucleus emits an electron and an antineutrino. Which nucleon conversion occurs inside the nucleus?
Radium-226 (^226_88Ra) undergoes spontaneous alpha decay (^4_2He). According to Soddy's conservation laws for nucleons (A) and charge (Z), what is the resulting daughter nucleus?
For the stoichiometric reaction A + 2B -> C in aqueous solution, how is the volumetric rate of consumption of reactant B related to the volumetric rate of formation of product C?
Chemistry
Which combination of experimental modifications will systematically accelerate the rate of a homogeneous liquid-phase chemical reaction?
What is the pH of an aqueous solution of hydrochloric acid (HCl, a strong monoprotic acid) with concentration C_a = 2.5 * 10^-3 mol/L at 25 degrees C? (Take log(2.5) ≈ 0.40)
What is the pH of an aqueous sodium hydroxide solution (NaOH, strong base) with concentration C_b = 1.0 * 10^-2 mol/L at 25 degrees C (where K_e = 1.0 * 10^-14)?
Loading more…