A.va=2m/s,vb=4m/s,vc=6m/s |
B.va=2m/s,vb=3m/s,vc=4m/s |
C.va=3m/s,vb=4m/s,vc=5m/s |
D.va=3m/s,vb=5m/s,vc=7m/s |
xac |
2T |
△x |
T2 |
A.3.5m | B.3m | C.2m | D.1m |
. |
v1 |
. |
v2 |
A.
| B.
| C.s1>s2 | D.s1<s2 |
A.250m | B.0 | C.240m | D.100m |
A.0、4m/s2、4m/s | B.4m/s、2m/s2、8m/s |
C.4m/s、1m/s2 8m/s | D.4m/s、2m/s2 、6m/s |
A.水平面 | B.球面 | C.抛物面 | D.不规则曲面 |
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