Cho mạch điện như hình vẽ: Biết: R1 = 15, R2 = R3 = R4 = 20; RA = 0; ampe kế chỉ 2A.
Tính cường độ dòng điện qua các điện trở R1, R2, R3, R4.

What is friction? how does it affect the motion of an object?

Chameleons catch insects with their tongues, which they can rapidly extend to great lengths. in a typical strike, the chameleon's tongue accelerates at a remarkable 220 m/s2 for 20 ms, then travels at constant speed for another 30 ms.

Friction removes energy from objects in motion. which statement best describes how this works? a) friction transforms ke into thermal energy b) friction transfers thermal energy to ke c) friction transforms te into pe d) friction transforms pe into ke e) friction transfers ke into pe