Answer:
B. 1200 J
Explanation:
Hello.
In this case, given the powers, we compute the energy transferred as shown below:
[tex]E=P*t\\\\E_1=60J/s*30s=1800J\\\\E_2=100J/s*30s=3000J\\\\Difference=3000J-1800J\\\\Difference=1200J[/tex]
Therefore, answer is B. 1200 J .
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