Lifting Mass

Though a straightforward application of Newton's second law, many find this problem deceptive. The common misconception which is carried into it is that the tension in the rope must equal the weight of the hanging object. When the mass is accelerated, that is not so. You may change the data and then click on either tension or acceleration in the equation below to calculate its value.

For a mass m= kg, the rope must support its weight = mg =Newtons to hold it up at rest. If the acceleration is a=m/s2 then a net force=Newtons is required to accelerate the mass. This requires a tension of T=Newtons. Note that the tension is equal to the weight only if the acceleration is zero, and that if the acceleration is negative (downward), the tension is less than the weight. If you enter a downward acceleration greater than 9.8 m/s2 you will get a negative tension, showing that you must force it downward to get an acceleration greater than that of free fall. See elevator problem 见电梯问题 对于质量为 m= kg 的物体，绳子必须承受其重量 = mg = 牛顿才能使其静止悬停。如果加速度是 a= m/s²，那么需要一个净力= 牛顿来加速该质量。这需要张力为 T= 牛顿。请注意，只有在加速度为零时，张力才等于重量；如果加速度为负（向下），则张力小于重量。如果你输入的向下加速度大于 9.8 m/s²，将得到负的张力，这表明必须迫使它向下以获得比自由落体加速度更大的加速度。 中文译文中的待填/计算数值依次对应：1：m 2：w 3：ac 4：nf 5：t。实际数值以上方原输入框为准。