New videos from Khan Academy 2021-05-05T14:03:49.000000
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Mató Nájin/Standing Bear (Minneconjou Lakota/Teton Sioux), Battle of Little Bighorn, c. 1920, pencil, ink, and watercolor on muslin, 91.4 × 268 cm, made in Pine Ridge Reservation, South Dakota, United States (The Metropolitan Museum of Art)
Hopi, White Ogre Tihu (Katsina Figure), c. 1900, cottonwood, pigment, cotton cloth, tanned leather, and metal, made in Arizona, United States, 47 × 15.2 × 17.8 cm (The Metropolitan Museum of Art); speaker: Brian Vallo, Director, Indian Arts Research Center School for Advanced Research, Santa Fe, New Mexico
Nampeyo (Hopi-Tewa), Polacca Polychrome Water Jar, c. 1895–1900, clay and pigment, made in Arizona, U.S., 30.5 × 34.3 cm (The Metropolitan Museum of Art); speakers: Gaylord Torrence, Fred and Virginia Merrill Senior Curator of American Indian Art, The Nelson Atkins Museum of Art and Brian Vallo, Director, Indian Arts Research Center School for Advanced Research, Santa Fe, New Mexico
Anishinaabe, possibly Mississauga Ojibwa, Shoulder bag (missing strap), c. 1800, tanned leather, porcupine quills, dye, glass beads, silk ribbon, metal cones, and deer hair, Possibly made in Ontario, Canada; possibly made in Michigan, United States; possibly made in Wisconsin, United States, 30.5 × 22.9 cm (The Metropolitan Museum of Art)
Acoma polychrome water jar, c. 1890, from Acoma, clay and pigment, 25.1 x 29.8 cm (The Metropolitan Museum of Art); speaker: Brian Vallo, Director, Indian Arts Research Center School for Advanced Research, Santa Fe, New Mexico
Ancestral Pueblo, Socorro black-on-white storage jar, c. 1050–100, clay and pigment, made in New Mexico, United States, 38.1 × 43.2 cm (The Metropolitan Museum of Art); speaker: Brian Vallo, Director, Indian Arts Research Center School for Advanced Research, Santa Fe, New Mexico
A conversation with Dr. Steven Zucker and Dr. Beth Harris in front of Petrus Christus, A Goldsmith in his Shop, 1449, oil on oak panel, 100.1 x 85.8 cm (The Metropolitan Museum of Art)
The Pyramid of the Moon and the Pyramid of the Sun, Teotihuacan, c. 1st century C.E., Mexico speakers: Dr. Lauren Kilroy-Ewbank and Dr. Beth Harris
A conversation between Dr. Kristen Brennan and Dr. Steven Zucker in front of a Zisha "Ru Ding" teapot made by Yang Pengnian, with Chen Mansheng mark, Yixing ware, c. late 18th–early 19th century (Shanghai Museum of Art) Note: the work was created with slabs of clay and then worked on a wheel. The term "thrown" may be misleading.
K and r are two extremes for a range of population growth strategies, no one strategy is better or best. Identify the characteristics associated with K selected and r selected species. Volunteer here: https://www.khanacademy.org/contribute
Vectors are quantities that have a magnitude and a direction. In the two-dimensional plane, we can describe them in an equivalent way, by thinking about the changes in x and y from the vector's tail to its head.
Vector quantities have both a magnitude and a direction. In this example, we interpret a mathematical statement about two vector quantities in terms of the real-world quantities they represent.
Vectors can represent real-world quantities where it's important to have both a magnitude and a direction. One example for that is force: you want to represent a force's magnitude (or strength), but it's also important to indicate in what direction the force is applied.
Practice using the rule of 70 to approximate population doubling time.
Relate the trends amongst human population growth rate and human population size.
Learn to apply the demographic transition model to populations.
The funerary bundle of the Señora de Cao, headdress ornament and six nose ornaments, found in what is now the El Brujo Archaeological Complex, c. 400 C.E., Moche (Museo Cao, Magdalena de Cao, Peru) A conversation with Dr. Sarahh Scher and Dr. Steven Zucker
Tsimshian, shaman's rattle, c. 1750–80, birch, bone, hair, pigment, and metal pins, made in British Columbia, Canada, 35.6 × 22.9 × 11.4 cm (The Metropolitan Museum of Art); speaker: Gaylord Torrence, Fred and Virginia Merrill Senior Curator of American Indian Art, The Nelson Atkins Museum of Art
Constant-pressure calorimetry is used to measure the change in enthalpy, ΔH, for a physical or chemical process. In this technique, a process is carried out in solution in a coffee cup calorimeter, an inexpensive device composed of two Styrofoam cups. The amount of heat transferred in the process (q) can be calculated from the mass, specific heat, and temperature change of the solution. Because the calorimeter is at constant (atmospheric) pressure, q is equal to ΔH for the process.
Bond enthalpies can be used to estimate the change in enthalpy for a chemical reaction. In this video, we'll use average bond enthalpies to calculate the enthalpy change for the gas-phase combustion of ethanol.