煤塊在傳送帶上有相對(duì)運(yùn)動(dòng),f=μmg=ma a=μg=2m／s^2
1,v1=4m/s
x1=v1t1+1/2at1^2 t1=2.47s
傳送帶位移
x2=v0t1=24.7m
劃痕 x2-x1=8.7m
2.v1=12m/s
減速時(shí)間 t1=(v0-v1)/-a=1s
減速位移 x1=(v0+v1)t1/2=11m
勻速時(shí)間 t2=(16-11)/10=0.5s
t=t1+t2=1.5s
劃痕 x=x1-v0t1=1m
3.v1=14m/s
x=v1t-1/2at1^2 t1=1.26s
劃痕 x=16-v0t1=3.4m
4.v1=8m/s
加速時(shí)間 t1=(10-8)/2=1s x1=(8+10)x1/2=9m
勻速 t2=(16-9)/10=0.7s
t=t1+t2=1.7s
劃痕 x=v1t-9=1m