如图所示，水平放置的轻弹簧左端固定，小物块P（可视为质点）置于水平桌面上的A点，并与弹簧右端接触，此时弹簧处于原长。现用水平向左的推力将P缓慢地推至B点，此时弹簧的弹性势能为E_p= 28J。撤去推力后，P沿桌面滑到一个上表面与桌面等高且静止在光滑水平地面上的长木板Q上，已知P、Q的质量均为m=2kg，A、B间的距离L₁=4m，A距桌子边缘C的距离L₂=2m，P与桌面及P与Q间的动摩擦因数都为μ=0.1，g取10m／s²，求：

（1）P刚滑到Q上时的速度大小；

（2）当Q的长度为3m时，试通过计算说明P是否会滑离Q。若不会滑离，则求出P、Q的共同速度大小；若会滑离，则求出当P滑离Q时，P和Q的速度各为多大？

阅读短文，从方框中选择适当的单词填空（每词限用一次）。

An old woman had a cat. The cat was very old. She could not run quickly, 小题1:_____she could not bite. One day the old cat saw a mouse. She jumped and caught the mouse. But she could not bite it, so the mouse got out of her mouth and ran小题2:_________.

Then the old woman became very 小题3:______because the cat had not killed the mouse. She began to hit the cat. The cat said, "Don’t hit your old 小题4:______. I have worked for you for many years, and I would work for you still, but I am too old. Do not be unkind 小题5:______ the old, but remember what good work the old did when they were young."