Problem: Extract the answer to the question from the following context. Question: When do universal motors operate on 1000 watts or less? Context: Operating at normal power line frequencies, universal motors are often found in a range less than 1000 watts. Universal motors also formed the basis of the traditional railway traction motor in electric railways. In this application, the use of AC to power a motor originally designed to run on DC would lead to efficiency losses due to eddy current heating of their magnetic components, particularly the motor field pole-pieces that, for DC, would have used solid (un-laminated) iron and they are now rarely used.

A: at normal power line frequencies

Problem: Extract the answer to the question from the following context. Question: Who were the Heike Monogatari? Context: In his book "Ideals of the Samurai" translator William Scott Wilson states: "The warriors in the Heike Monogatari served as models for the educated warriors of later generations, and the ideals depicted by them were not assumed to be beyond reach. Rather, these ideals were vigorously pursued in the upper echelons of warrior society and recommended as the proper form of the Japanese man of arms. With the Heike Monogatari, the image of the Japanese warrior in literature came to its full maturity." Wilson then translates the writings of several warriors who mention the Heike Monogatari as an example for their men to follow.

A: warriors

Problem: Extract the answer to the question from the following context. Question: If one parent is white and one is native, the child is? Context: The social identity of the children was strongly determined by the tribe's kinship system. Among the matrilineal tribes of the Southeast, the mixed-race children generally were accepted as and identified as Indian, as they gained their social status from their mother's clans and tribes, and often grew up with their mothers and their male relatives. By contrast, among the patrilineal Omaha, for example, the child of a white man and Omaha woman was considered "white"; such mixed-race children and their mothers would be protected, but the children could formally belong to the tribe as members only if adopted by a man.

A: mixed-race

Problem: Extract the answer to the question from the following context. Question: What causes gravitational potential energy to be stored? Context: Examples of energy transformation include generating electric energy from heat energy via a steam turbine, or lifting an object against gravity using electrical energy driving a crane motor. Lifting against gravity performs mechanical work on the object and stores gravitational potential energy in the object. If the object falls to the ground, gravity does mechanical work on the object which transforms the potential energy in the gravitational field to the kinetic energy released as heat on impact with the ground. Our Sun transforms nuclear potential energy to other forms of energy; its total mass does not decrease due to that in itself (since it still contains the same total energy even if in different forms), but its mass does decrease when the energy escapes out to its surroundings, largely as radiant energy.

A:
crane motor