Tính điện trường của sợi dây AB có độ dài 2a, tích điện với mật độ điện dài λ, gây ra tại điểm H trên đường vuông góc với trung điểm dây (hình vẽ 1). Khoảng cách
đoạn OH = h. Xét trường hợp đặc biệt khi a→∞.

Which of the following situations is impossible? a) an object has velocity directed east and acceleration directed east. b) an object has zero velocity but non-zero acceleration. c) an object has constant non-zero velocity and changing acceleration. d) an object has velocity directed east and acceleration directed west. e) an object has constant non-zero acceleration and changing velocity.

Apersons beliefs and general outlook, which act like filters on the information they receive are called ?

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)