△B |
△t |
B |
t |
△Φ |
△t |
2BL2 |
t |
E1 |
R |
4B2L4 |
Rt |
1 |
2 |
E2 |
R |
4B2L2v1 |
R |
v22-v12 |
4L |
4B2L2v1 |
mR |
1 |
2 |
1 |
2 |
m(v22-3v12) |
4 |
4B2L4 |
Rt |
v22-v12 |
4L |
4B2L2v1 |
mR |
m(v22-3v12) |
4 |
A.保持θ角不变,使玻璃管加速上升 |
B.沿顺时针方向缓慢转动玻璃管,使θ角变小 |
C.使环境的温度升高 |
D.绕过b端的竖直轴匀速转动 |
A.a1=a2=0 | ||||
B.a1=a,a2=0 | ||||
C.a1=
| ||||
D.a1=a,a2=
|
A.mg | B.μmg | C.mg
| D.mg
|
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