Path length is 2*pi*0.4=2.512
Speed=distance/time
Speed =2.512/0.2=12.56m/s
Answer b protons and electrons
Answer:
The electron's speed is 34007.35 m/s
Explanation:
It is given that,
Magnetic field, B = 0.34 T
Magnetic force on the electron, 
The electron follows a helical path. We have to find the speed of an electron. The formula for magnetic force is given by :

q = charge on an electron, 
v = velocity of an electron


v = 34007.35 m/s
Hence, this is the required solution.
They live half their lives in water and most of their life on land