Một dây dẫn thẳng dài vô hạn có dòng điện I = 15A chạy qua. Hãy xác định vecto cường độ từ trường tại điểm M cách dòng điện một đoạn R = 2cm. Biết dòng điện đặt trong chân không

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 11.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.80 m/s; (b) he is then lifted at the constant speed of 4.80 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 78.0 kg rescue by the force lifting him during each stage

Which simple machine is not part of this compound machine? a. lever b. pulley c. inclined plane d. wheel and axle

Science and technology are interdependent. advances in one lead to advances in the other. give an example of this phenomenon.