Answer:
58 seconds
Step-by-step explanation:
Given:
Initial mass of water = 1 kg
Specific energy = 2297 kJ/kg
Heat supplied by the stove = 20 kJ/s
Now,
Half water is to be vaporized i.e 0.5 kg
Thus, heat required for vaporizing 0.5 kg water = mass × specific heat
or
heat required for vaporizing 0.5 kg water = 0.5 × 2297 = 1148.5 kJ
Therefore,
time taken to provide the required heat = 
or
time taken to provide the required heat = 
or
time taken to provide the required heat = 57.425 ≈ 58 seconds
The answer is 276,000.
Hope that helps :]
Answer:
50 minutes left.
Step-by-step explanation:
The easiest way to do this is to convert all the fractions into <em>minutes</em>
<em />
So, she would've spent <u>1 hour and 30 minutes</u> on her homework and <u>40 minutes on her telephone</u>. If you <u>add</u> those amounts up, you get <u>2 hours and 10 minutes</u>. Since she goes to bed <u>3 hours after dinner</u>, and <u>2 hours and 10 minutes have gone by</u>, you do 3 hours - 2 hours 10 minutes and you get 50 minutes.
Hope that makes sense. Let me know if you have any questions.
