Trường hợp nào dưới dây có thể coi là chất điểm A. trái đất trong CĐ tự quay quanh mình nó với nhau
B. hai hòn bi lúc va chạm
C. người nhảy cầu lúc đang rơi xuống nước
D. giọt nước mưa lúc đang rơi

6–55 refrigerant-134a enters the condenser of a residential heat pump at 800 kpa and 358c at a rate of 0.018 kg/s and leaves at 800 kpa as a saturated liquid. if the compressor consumes 1.2 kw of power, determine (a) the cop of the heat pump and (b) the rate of heat absorption from the outside air.

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

Balloon a has charge q, and identical mass balloon b has charge 10q. you hang them from threads near each other. choose all of the statements with which you agree. check all that apply. a. a and b exert the same magnitude forces on each other. b. the force that a exerts on b is 10 times the force that b exerts on a. c. the angle between the thread supporting a and the vertical is < the angle between the thread supporting b and the vertical. d. the force that a exerts on b is 1/10 the force that b exerts on a.