But that scattering changes the momentum of the electron in an unpredictable way.

但是这种散射以一种不可预测的方式改变了电子的动量。

Instead, impulse -- usually represented by a J -- is the integral of the net force on an object over time -- in other words, its change in momentum.

相反，脉冲 - 通常由J表示 - 是物体随时间推移的净力的积分 - 换句话说，它的动量变化。