Capacitor/Charging & magnetic Field

[Drooling]

1) A particle of mass 7.7 x 10-8 kg and charge +6.8 μC is traveling due east. It enters perpendicularly a magnetic field whose magnitude is 2.5 T. After entering the field, the particle completes one-half of a circle and exits the field traveling due west. How much time does the particle spend in the magnetic field?

3) A proton is projected perpendicularly into a magnetic field that has a magnitude of 3.4 T. The field is then adjusted so that an electron will follow the exact same circular path when it is projected perpendicularly into the field with the same velocity (same magnitude and same direction) that the proton had. The mass of the electron is 9.11 × 10-31 kg, and the mass of the proton is 1.67 × 10-27 kg.

(b1) What is the magnitude Be of the magnetic field used for the electron?

I need help in this 3 question. How do i solve it?

 

[edziura]

"1) A particle of mass 7.7 x 10-8 kg and charge +6.8 μC is traveling due east. It enters perpendicularly a magnetic field whose magnitude is 2.5 T. After entering the field, the particle completes one-half of a circle and exits the field traveling due west. How much time does the particle spend in the magnetic field?"

Some hints: the force acting on the particle is the magnetic portion of the Lorentz force; Newton's 2nd law; uniform circular motion.

 

[Drooling]

I am totally clueless!`

 

[edziura]

the force acting on the particle is the magnetic portion of the Lorentz force; Newton's 2nd law; uniform circular motion

Did you look up these topics in your textbook?