压力与力 力 力是物体上的拉力或推力,它可以改变物体的速度。我们可以说,如果从一个方向对物体施加力,并且没有相反的力,那么物体就会运动。如果它已经在移动,它会变快或变慢,这取决于所施加的力的方向。 这可...
...算汽车加速速度时,了解扭矩也很有用。 什么是力(force)? 定义: 力是发生的某种作用,它使物体保持运动或以某种方式改变物体的运动。这个概念是基于牛顿的三个运动定律。力是一个矢量,因为它不仅有大小,而且有一...
...nd the table pushes back up on the apple ( ). The apple is at rest, so the forces on the apple are balanced (according to Newton’s first law). This way, the upward push on the apple by the table ( ) is balanced by the downward pull on the apple by Earth (due to gravity) ( ). It is important to not...
...ow to calculate work done. Work is done when the point of application of a force moves along the force’s line of action. The line of action of the force is a line drawn through the point of application in the direction of the force. Suppose a c***tant force acts on an object and causes the obje...
...,而压力被定义为垂直于单位面积表面的力。 什么是力(force)? 根据牛顿第二定律,我们可以把力描述为一种相互作用,这种相互作用具有引起加速度的能力。当然,如果物体上的净力为0,那么就不会有净加速度。更简单地说...
...etween two surfaces is given by where is the size of the normal contact force between the two surfaces. is called the coefficient of static friction and has a c***tant value for two types of surfaces. e.g. for steel on steel is about 0.74 while for aluminium on steel it is about 0.61. 什...
...,作用在物体上的净力不是0。 什么是平衡的力量(balanced forces)? 作用在物体上的力是平衡的,如果它们的矢量和为0,即没有作用在物体上的净力。根据牛顿运动定律,物体不会加速。这意味着,如果身体处于静止状态,它将继...
...率。另一方面,力指的是力传递能量的速率。 什么是力(force)? 力是能够使物体改变动量的东西。力由动量变化率给出: 力的单位是牛顿(N)。1牛顿的力相当于一个苹果的重量。 通常,力被描述为推或拉。你需要一个力来改...
...力引起的长度的相对变化。 什么是强调(stress)? Whenever a force attempts to deform an object, we say that the object is under stress. Stress is defined as the deforming force per unit area of the object. Since we can resolve any force on an object into directi*** parallel and perpe...
...“moment” to mean the “torque” that an object experiences due to a force. The torque about any point due to a force is given by the cross product between and the vector drawn from the point we are interested in, to the point where force is applied: Defining Torque 力矩的大...