A5 3 m/s
3B20 m/s C20 3 m/s
3D5 m/s
6
A
B
C
D
7
A B C D
82019 410
R
G6.67 10 11N? m
2/kg c3.0 10 8m/s M
6.0 10 24kg
A910 6m B910 3m C9m D9 10 3m
9
A B
C D
10 Q+2Q r
F
A4F B2 F C DF
11
O
12
3
A O
B
C
D
12 AB
