根据句意及首字母提示补全单词。

1. When I found him, he was cutting his hair in a b         shop.

2. No one knew what h         before they came to the museum.

3. While she was in the kitchen, she heard someone s         for help.

4. They were talking to some police o         in the park at that time.

5. Some children were s         when they saw the terrible animal.

对于两物体碰撞前后速度在同一直线上，且无机械能损失的碰撞过程，可以简化为如下模型：A、B两物体位于光滑水平面上，仅限于沿同一直线运动，当它们之间的距离大于等于某一定值d时，相互作用力为零；当它们之间的距离小于d时，存在大小恒为F的斥力，设A物体质量m₁=1.0kg，开始时静止在直线上某点；B物体质量m₂=3.0kg，以速度v₀从远处沿该直线向A 运动，如图所示，若F=0.60N，v₀=0.20m/s，求：

（1）相互作用过程中A、B加速度的大小；

（2）从开始相互作用到A、B间的距离最小时，系统（物体组）动能的减少量．