In mechanics, luggage in the two words, even in the middle of the place such as the stair is still just tilt, there will not be an easy and which is tired, heavy and light just psychological effect!

• 以力学而言，行李在两个人正中间的话，即使是在像楼梯这种倾斜的地方仍然是刚好平均分摊，并不会有哪一方比较轻松和比较累的，重与轻只是心理作用而已！