Electric field due to a point charge is given as

here we know that

also the distance is given as

now we will have

so we will have

so above is the electric field due to proton
the rate of work done or doing work is usually measured by the power of a machine .
Answer:
a
The time it would take the beef to reach a temperature of 0⁰C is t= 662 sec = 11.93 min
b)
The time it would take to heat the beef to uniform temperature of 80⁰C is
t = 365 sec =5.93 min
c
Efficient absorption of Microwave power is in regions of liquid water . Hence if the food or the microwave irradiation is not uniform, the power will be absorbed non-uniformly, resulting in a non-uniform temperature rise. Defrost region will absorb more energy per unit volume than frozen region.if food is of low thermal conductivity, there will be insufficient time for heat conduction to make the temperature more uniform.Use of low power allows more time for conduction to occur.
Explanation:
The explanation is shown on the first second and third uploaded image