Answer:
Electric field acting on the electron is 127500 N/C.
Explanation:
It is given that,
Mass of an electron, 
Charge on electron, 
Initial speed of electron, u = 0
Final speed of electron, 
Distance covered, s = 2 cm = 0.02 m
We need to find the electric field required. Firstly, we will find the acceleration of the electron from third equation of motion as :



According to Newton's law, force acting on the electron is given by :
F = ma


Electric force is given by :
F = q E, E = electric field


E = 127500 N/C
So, the electric field is 127500 N/C. Hence, this is the required solution.
Explanation:
Given that,
Mass, m = 0.08 kg
Radius of the path, r = 2.7 cm = 0.027 m
The linear acceleration of a yo-yo, a = 5.7 m/s²
We need to find the tension magnitude in the string and the angular acceleration magnitude of the yo‑yo.
(a) Tension :
The net force acting on the string is :
ma=mg-T
T=m(g-a)
Putting all the values,
T = 0.08(9.8-5.7)
= 0.328 N
(b) Angular acceleration,
The relation between the angular and linear acceleration is given by :

(c) Moment of inertia :
The net torque acting on it is,
, I is the moment of inertia
Also, 
So,

Hence, this is the required solution.