Answer:
(a). The speed of electron is
.
(b). The radius of electron is 
Explanation:
Given that,
Length = 2.5 cm
Distance = 6.0 mm
Magnetic field = 2.1 T
Potential difference = 700 V
(a). We need to calculate the electron's speed
Using formula of speed

Put the value into the formula



(b). We need to calculate the radius of electron
Using formula of centripetal force


Where,
m = mass of electron
v = speed of electron
r = radius
q = charge of electron
B = magnetic field
Put the value into the formula



Hence, (a). The speed of electron is
.
(b). The radius of electron is 4.2 cm
Answer:
434.16 Joules
Explanation:
u = Initial velocity
v = Final velocity
m = Mass of person
From work-energy theorem

The runner loses 434.16 Joules of mechanical energy.

He slides 0.94364 m
Number two is the Alpha particle
Number one is the Gamma-ray
Number three is the Beta particle
Hope this helped.