[填空题]
A 21.7-kg child descends a slide 3.5 m high and .rpvqfn 2(jr5 reazkw a(,dngeu7 ek)4a d+2+gly q2(yweches the bottom with a speed of 2.2m/s How muu zyeydeq+ 2alengw(2wd+k4 g7a ( ),kch thermal energy due to friction was generated in this process? J
