1.F-f=ma.
L =1/2at*2.代入数据得,f =10,所以u =0.5
2.Fcosa-f=ma1
xi=1/2a1t*2=7/2t *2
v=at1=7t1
x2=vt2-1/2a2t2*2=7t1t2-5/2t2*2
且,x1+x2=20
所以,t1=三分之根下四十二,t2=二十一分之五倍的根下二,
从而得t =t1+t2 =(4J42)/7
1.F-f=ma.
L =1/2at*2.代入数据得,f =10,所以u =0.5
2.Fcosa-f=ma1
xi=1/2a1t*2=7/2t *2
v=at1=7t1
x2=vt2-1/2a2t2*2=7t1t2-5/2t2*2
且,x1+x2=20
所以,t1=三分之根下四十二,t2=二十一分之五倍的根下二,
从而得t =t1+t2 =(4J42)/7