Cơ năng của một vật được bảo toàn khi nào

If a tank filled with water contains a block and the height of the water above point a within the block is 0.8 meter, what is the pressure at point a?

Based on the concept of the wave-like nature of light, huygens' theory of light postulates that the more light was "bent" by a substance the slower it would move while traversing across that substance. a) deflection b) interference c) refraction d) resonance

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.