一列火车在 20 s 内从 15 m/s 匀减速到 10 m/s。 这段时间内它行驶了多远?求 s。
求: s (m)
显示提示
- 加速度恒定时,平均速度是初速度与末速度的平均值。
- s = (v₀ + v)/2 · t。它是 v–t 图线下的面积。
- 平均速度 = 12.5 m/s.
显示答案和分步解答
Motion with constant acceleration: v = v₀ + a·t, s = v₀·t + ½·a·t² and v² = v₀² + 2·a·s. Pick the equation that contains the three things you know and the one you want, and keep the signs consistent with one positive direction.