- #1
mbrmbrg
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Homework Statement
In Figure 28-28 (see attached), a charged particle enters a uniform magnetic field B with speed v0, moves through a half-circle in time T0, and then leaves the field.
Which statements are true? (Select all that apply.)
- The charge is positive.
- The charge is negative.
- The final speed of the particle is greater than v0.
- The final speed of the particle is less than v0.
- The final speed of the particle is equal to v0.
- For an initial speed 0.5v0, T > T0.
- For an initial speed 0.5v0, T < T0.
- For an initial speed 0.5v0, T = T0.
- For an initial speed 0.5v0, the path is more than a half-circle.
- For an initial speed 0.5v0, the path is less than a half-circle.
- For an initial speed 0.5v0, the path is also a half-circle.
Homework Equations
[tex]F_B=qv\times B[/tex]
[tex]F_c=\frac{mv^2}{r}[/tex]
The Attempt at a Solution
I'm fine until I'm asked to halve the velocity. I combined my two equations and found that when v'=0.5v, r'=0.5r. but I'm not sure how that affects the shape of the trajectory. Will the particle still make a semicircle, only now with a smaller radius? If so, it would make sense that the t'>t. But on the other hand, a smaller velocity should result in a longer time!
I guessed 2, 5, 7, & 11, then I tried 2, 5, 6, & 11. Both combinations are incorrect.
I'd appreciate any help in understanding how velocity affects the trajectory and time. Thanks!