Cho 1 đoạn mạch gồm 2 điện trở R1 và R2 mắc // và mắc vào 1 hiệu điện yhees không đổi . Nếu giảm trị số của điện trở R2 thì

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

A-of 75 cm by cm by 17.5 cm up. of is 2 kg a , in ,if it is in , kg/?

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body