A 50 kg block of wood is pressed against a smooth wall by a

来源：学生作业帮编辑：作业帮分类：物理作业时间：2024/08/28 07:25:44

A 50 kg block of wood is pressed against a smooth wall by a force perpendicular to the wall.If the coefficient of static friction is 0.13 ,what is the minimum force that is necessary to keep the block of wood in place?
模糊的翻译:
一个50 公斤木块被按没光滑的墙壁由力量垂线对墙壁.如果静态摩擦系数是0.13,以最低到什么的力量来保持木块到位?
At what altitude above the Earth's surface would the gravitational acceleration be 4.9m/s^2 The mass of the Earth is 5.98 x 10^24 kg and radius is 6.37 x 10^6 m
模糊翻译:
在什么高度在地球之上表面重心加速度会是4.9m/s^2?地球的重量是5.98 x 10^24 公斤并且半径是6.37 x 10^6 m.

第一题:
50Kg的木块被压在光滑墙壁上,压力和墙面垂直,静摩擦系数为0.13,为了让木块保持静止,至少要多大的压力.
因为是光滑墙壁,所以只有手和木块的接触面上有静摩擦,
要使木块不滑动,摩擦力就不能小于重力,所以最小摩擦力
等于重力,于是
F x 0.13 =50g
压力F便可求得
第二题：
在多高的时候,重力加速度的数值是4.
重力其实是万有引力的一个分力,但根据本题题意,不考虑
地球自转的情况下,重力就近似于万有引力.
设地球的质量为M,半径是R;在高度h处,有一质量为m的物体,
且此高度处的重力加速度g=4.5
则,
GMm/(R+h)^2 = mg
(左边是万有引力,右边是重力)
把m消掉就可以求得高度h了.

英语翻译One day he was handed a piece of paper,a block of wood a One day he was handed a piece of paper,a block of wood and f paper is often made()wood.A:by B:in C:of 要说原因. 英语翻译Harbors Collection by Hallmark Wood is a factory direct I back handed him against a wall. beat one's head against a wall against a background of On a map whose scale is 1:50000 ,a wood is represented by a Is there a f( ) in front of block my shoes ___ my feet and they hurt___.A.are pressed against, The table is made _ wood and the paper is made _ wood A.of,o 英语翻译The value of a block of land has increased by 20% of the