Answer:
Heat energy required = 252000J or 252KJ.
Explanation:
<u>Given the following data;</u>
Mass = 3kg
Temperature = 20ºC
Specific heat capacity of water = 4200 J/kg°C
To find the heat energy required;
Heat capacity is given by the formula;
Where;
- Q represents the heat capacity or quantity of heat.
- m represents the mass of an object.
- c represents the specific heat capacity of water.
- t represents the temperature.
Substituting into the equation, we have;
Q = 252000 Joules or 252 Kilojoules.
Answer:
Option A is the correct answer.
Explanation:
Here momentum is conserved.
That is 
Substituting values

Speed of block A after collision = 10 m/s
Option A is the correct answer.
A, Lenz' Law. There need to be a difference of flux, so if you use AC you will get a current too.
2 is the answer so mark it