Phát biểu nào sau đây là đúng ? A. Thế năng của lực hấp dẫn của chất điểm là một hằng số
B. Mmốc tính thế năng đàn hồi được chọn tùy ý
C. Độ giảm thế năng bằng công của lực bảo toàn thực hiện lên vật

What is the conversion factor between kg/m^3 and g/m^3. express your experimental values for the densities in kg/m^3.

Aplayground merry-go-round has a radius of 4.6 m and a moment of inertia of 200 kg-m2 and turns with negligible friction about a vertical axle through its center. a child applies a 26.0 n force tangentially to the edge of the merry-go-round for 15.0 seconds. if the merry-go-round is initially at rest, how much work did the child do on the merry-go-round?

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?