Topic content:
The correct one of the following statements is ()
A. A static object suspended on a rope is subject to the same force of gravity as the force that tightens the rope
B. Objects on the earth are subject to gravity only when they are still
C. The same object receives the maximum gravity when moving downward and the minimum gravity when moving upward
D. The same object in the same place, regardless of its state, receives the same gravity
Best answer:
A、 Gravity belongs to gravitation, while tension belongs to elasticity, so option A is wrong
B、 Any object on the earth is subject to gravity and is not affected by the state of motion, so option B is wrong
C、 The gravity of the same object remains unchanged and is not affected by the motion state, so the C option is wrong
D、 The same object in the same place, regardless of its state, receives the same gravity, so the D option is correct
Therefore: D
Answer analysis:
There is no explanation for this question
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