какую энергию нужно затратить, чтобы расплавить кусок свинца массой 8 килограмм , взятый при температуре 27 градусов ? удельная теплота плавления свинца 0,25* 10^5Дж/кг температура плавление свинца 327градусов

In which of the following cases is work being done on an object? question 2 options: pushing against a locked door carrying a box down a corridor pulling a trailer up a hill suspending a heavy weight with a strong chain

What is the primary force that suspension bridges use cables to hold their spans up? a. tension force b. resistance force c. normal force d. elastic force e. applied force

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?