Question

关于作用力和反作用力的物理问题

Answer 1

Before wering your questions
you need to be aware that action (作用力) and reaction (反作用力) act on different bodies. Hence
they cannot cancel each other out. 1) 因为身体施加于椅子的作用力和椅子所给的反作用力是相等的
所以不论椅子如何破损
椅子永远坐不破. The action is the force exerted on the chair. This force would break the chair if the chair was not strong enough. The reaction force acts on the body and which balances the body weight. Note that if the chair is broken
the reaction force might be *** aller than the body weight
and the person would fall. (2) 不论对墙施以多少力
它总是以同等的力把你推回去.因此该墙不论被施以多大的力
它总是推不倒. The wall collapses because of the pushing force that you exert on it. The reaction force is experienced by you
not by the wall. Hence
the wall is only subjected to the action force. (3) 由于作用力和反作用力相等
一个人跳起时因为跳起者对地板所施的作用力阻止反作用力把跳起者往上推.因此该个人永远跳不起. You have already said that the action force is exerted on the ground "跳起者对地板所施的作用力"
NOTon the person. How e this force would prevent the person to jum up. (4)当作用力和反作用力相等时
一个人能站在地板上.当作用力大于反作用力时
该个人会踩破地板.当作用力小于反作用力时
那个人能跳起. No
this is not correct. A man stands firmly on the floor because his weight (which is given by the earth) is balanced by the "normal reaction" given by the floor. The "normal reaction" arises due to the force exerted on the floor by the man (this is the action force). Because the "weight" is constant
if the floor breaks
the "normal reaction" force given by the floor diminishes and the man falls. If the man exerts an additional force (i.e. increasing the action force) onto the floor
the "normal reaction" will increase accordingly. Because "weight" is constant
the normal reaction force is now larger than the weight
the man thus jumps up.
第一
我肯定你上堂冇听书 作用力同反作用力系施系不同物件上面
A向B施加一道力
B会向A加一道力度相等但方向相方既力 所以只有一道力施向A
一道力施向B
佢地唔会抵消自己 所以你所讲既情况全部唔成立
参考: 常识
反作用力不是用来抵消作用力
而且两者所施在的物件不同. 应该分开谂 1.椅子所给的反作用力是对于身体
而不是身体所施椅子的作用力 而你所说的椅子永远坐不破是认为反作用力抵消了作用力
当身体所施椅子的作用力大于椅子最多能受的力
椅子就会破. 2.同上 3.当反作用力少于weight
人就不会跳起
4. 作用力和反作用力的定义是 equal magnitude
opposite direction
acting on different object 踩破地板同坐破椅子一样 如果反作用力大过weight 人就会跳起 2012-03-13 00:15:11 补充： 反作用力不是用来抵消作用力
而且两者所施在的物件不同. 应该分开谂 1.椅子所给的反作用力是对于身体
而不是身体所施椅子的作用力 而你所说的椅子永远坐不破是认为反作用力抵消了作用力
当身体所施椅子的作用力大于椅子最多能受的力
椅子就会破. 2.同上 3.当反作用力少于weight
人就不会跳起
4. 作用力和反作用力的定义是 equal magnitude
opposite direction
acting on different object 踩破地板同坐破椅子一样 如果反作用力大过weight 人就会跳起