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標題:
質量m的物體
發問:
質量m的物體 靠於鉛直牆上與牆間之靜摩擦係數為us 今施ㄧ水平力F於物體 使物體不滑下 下列何者正確 1.F=mg 2.mg=usF 3.牆與物體間之磨擦力為mg 4.牆施於物體之淨力(合力)為F*根號1+us平方 5.若物體與牆無磨擦 則F無論多大均不能平衡 錯誤的地方如何修正 更新: 答案是3.5
最佳解答:
Statement 2 is correct. Friction Ff = mg but Ff = (us)R = (us)F where R is the normal reaction, which acts horizontally opposite to direction of F Statement 3 is correct. The frictional force is acting upward, which balances the downward weight mg Statement 4 is correct Net force = square-root[R^2 + Ff^2] = square-root[R^2 + (us,R)^2] = R.square-root(1+us^2) = F.square-root(1+us^2) Statement 5 is correct. Fis horizontally acting, it cannot balance the vertically acting weight mg
質量m的物體
發問:
質量m的物體 靠於鉛直牆上與牆間之靜摩擦係數為us 今施ㄧ水平力F於物體 使物體不滑下 下列何者正確 1.F=mg 2.mg=usF 3.牆與物體間之磨擦力為mg 4.牆施於物體之淨力(合力)為F*根號1+us平方 5.若物體與牆無磨擦 則F無論多大均不能平衡 錯誤的地方如何修正 更新: 答案是3.5
最佳解答:
Statement 2 is correct. Friction Ff = mg but Ff = (us)R = (us)F where R is the normal reaction, which acts horizontally opposite to direction of F Statement 3 is correct. The frictional force is acting upward, which balances the downward weight mg Statement 4 is correct Net force = square-root[R^2 + Ff^2] = square-root[R^2 + (us,R)^2] = R.square-root(1+us^2) = F.square-root(1+us^2) Statement 5 is correct. Fis horizontally acting, it cannot balance the vertically acting weight mg
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