Cho mạch điện như hình vẽ tìm các dòng I1, I2 , I3 và I4 biết E1 = 120V, E2 = 60V, J = 10A, R1= R2= 20Ω. R3= R4= (10 + K) Ω
(k=5)

Which is not a characteristic of a heat pump? a. it is used in air conditioners. b. it uses a refrigerant. c. it requires no work. d. it reverses the normal flow of thermal energy.

Acompound machine is also called a machine. a. force b. simple c. complex d. directional

What properties of a moving object are used in determining the object's energy of motion