在水平面上拉动物体作匀速运动时,拉力与地面所成的夹角大省力,还是夹角小省力?对这个问题学生有两种认识;一种认为θ角越小越省力,理由是θ角越小拉力沿运动方向的分力就越大,因此省力.另一种认为θ角越大越省力,理由是拉力在竖直方向的分力增大 When the animal is pulled in a horizontal plane and moves at a constant speed, the angle between the pulling force and the ground is large and labor-saving, or is the angle between the two sides small and labor-saving? There are two kinds of knowledge for students in this problem; one thinks that the smaller the angle θ, the less effort, the reason is the angle θ The smaller the pull force along the direction of movement, the greater the force component. Therefore, the other is that the larger the angle θ is, the more effort it saves. The reason is that the force component of the pulling force increases in the vertical direction.