A toaster oven uses67,500 joules of energy in 45 seconds to toast a piece of bread what is the power of the oven

1 answer:

7 0

If you simply divide joules by seconds, the answer is in units
of joules/sec (watts) which is exactly what you want.

(67,500 joules) / (45 sec) = 1,500 joules/sec = 1,500 watts

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an object with a mass of 6 kilograms accelerates 4.0 MS to the second when an unknown force is applied to it what is the amount

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4 years ago

A hot-water bottle contains 787 g of water at 75∘C. If the liquid water cools to body temperature (37 ∘C), how many kilojoules o

IgorC [24]

Answer:

$Q = 787 gr * 1 \frac{cal}{gr C} *(37-75)C = -29906 cal$

So then the answer for this case would be 29906 cal but we need to convert this into KJ and we know that 1 cal = 4.184 J and if we convert we got:

$29906 cal *\frac{4.184 J}{1 cal}* \frac{1KJ}{1000 J}= 125.127 KJ$

Explanation:

For this case we know the mass of the water given :

$m = 787 gr$

And we know that the initial temperature for this water is $T_i =75 C$ .

We want to cool this water to the human body temperature $T_f = 37 C$

Since the temperatures given are not near to 0C (fusion point) or 100C (the boling point) we don't need to use latent heat, then the only heat involved for this case is the sensible heat given by:

$Q= m c_p \Delta T$