[填空题]
In Problem 79 (Fig. 7–46), wps7 d;jwp0 +xkhat is the upper lime, vnh2hprjb e evy07uvzt2: i10w-8/lho9e tit on mass m if it is to rebound from M, slide up the incline, stop, slnt:h7j yb2/v0 tz8h01e9 pvi 2rl-, ehovueewide down the incline, and collide with M again? kg (Let A represent mass m, and B represent mass M.)