Topic content:
The following statement about the center of gravity of an object is correct ()
A. The center of gravity is the heaviest point on the object
B. The center of gravity of a regularly shaped object must be at its geometric center
C. The center of gravity is the acting point of gravity on the object, so it must be on the object
D. Hang the thin plate with a thin line and keep it still. The center of gravity of the thin plate must be on the straight line where the thin line is located
Best answer:
D
Answer analysis:
The center of gravity is the acting point of gravity, not the heaviest point on the object; The center of gravity of an object with regular shape and uniform mass distribution is at its geometric center; The center of gravity is the acting point of gravity on the object, but not necessarily on the object; Hang the thin plate with a thin line and keep it still. According to the force balance knowledge, the center of gravity of the thin plate must be on the straight line where the thin line is; Option D is correct.
Test core:
Gravity:
1. The generation of gravity: objects near the ground are attracted by the earth, which is called gravity. All objects near the ground are subject to gravity, which is called weight for short. The unit of gravity is N, but the symbol is G. explain:
(1) It is caused by the gravity of the earth, but it cannot be said that gravity is the gravity of the earth. M is the mass of the object, and g is the acceleration of gravity. Generally, 9.8N/kg (9.8m/s2) is taken, meaning that 9.8N is applied to each kilogram of mass.
(1) Gravity at the two poles is equal to universal gravitation, universal gravitation at the equator=gravity+centripetal force (2) When the earth rotation is not considered, gravity can be considered equal to universal gravitation (3) Generally, the higher the latitude is, the greater the g value is (4) It has nothing to do with the motion state of the object. 3. The direction of gravity: the direction is always vertical downward, not necessarily pointing to the center of the earth (only at the equator and the poles pointing to the center of the earth).
(1) It does not necessarily point to the center of the earth, but only at the poles or equator. (2) The direction of gravity points to the center of the earth, The center is at its geometric center (3) The center of gravity is not necessarily on the object (4) The position of the center of gravity is independent of the motion state, spinning mode and position of the object