Which theorems are the most important in high school physics

Which theorems are the most important in high school physics

The stability of equilibrium, the transformation of reference frame (classical and relativistic (Lorentz transformation)) system, inertia force, momentum theorem of system, konich theorem, angular momentum theorem, functional principle and conservative force, potential energy, inertial potential energy, vibration equation and wave function, Huygens principle, standing wave, Kramer

Only after the reference frame is selected, can the motion of the object be determined?
Right or wrong

Except for the light, but high school doesn't matter

A physics problem in grade two of junior high school
In order to measure the paper thickness of a physics textbook, a student adopted the following measures:
A. Measure the thickness of a book and mark it as L;
B. Select the triangle ruler and check whether the zero scale line is worn;
C. Turn to the page number on the last page of the physics book and mark it as n;
D. Use d = L / N to express the thickness d of each paper in physics book
(1) What are the wrong steps in the above measures
Should be changed to
(2) After the correction of experimental measures, the correct experimental steps should be (fill in the letter number)

Answer: (1) there are two wrong steps: change a ~ B to B ~ a D, if yes, but the page number: D = L / N is double page number: D = L / 2n (...)

It takes 2.5 seconds for the laser to be sent from the ground to the moon and returned to the earth by the surface of the moon______ ．

Laser is a kind of electromagnetic wave with propagation velocity of 3 × 108m / S; the distance of laser from the ground to the moon and then from the moon to the earth is s = VT = 3 × 108m / s × 2.5s = 7.5 × 108m; the distance from the moon to the earth is s' = 12s = 12 × 7.5 × 108m = 3.75 × 108m