2019-2020
1
A
B
C
D 0 0
2 -
( )
A
B 20s
C20s
D40s
3 m AB
B N T
AN T BN T
CN T DN T
4 10m/s 45
g10m/s2
A 15m B 10m
C 10m D 20m
5
10N 10N .