CoachAn inclined plane — a ramp — is a slope for raising loads without lifting them straight up. The gentler the slope, the smaller the push needed to move the load along it: rolling a barrel up a long, gentle ramp is easy; up a short, steep one, brutal; straight up, impossible.
示例
Example 31.7 (Ramps in the landscape)
Wheelchair ramps run long and shallow beside short staircases — gentleness on purpose. Mountain roads zigzag: rather than attack the summit straight up, they wrap a long, gentle inclined plane back and forth across the slope. And the screw is a ramp in disguise — a slope wrapped around a rod, so each easy turn of the screwdriver sneaks the screw a tiny step deeper.