Exercise 6.4 A frost-free refrigerator uses 640 kWh of electrical energy per yea

Question

Exercise 6.4

A frost-free refrigerator uses 640

kWh

of electrical energy per year.

Part A

Express this amount of energy in

J

.

Express your answer using three significant figures.

2.45

J

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Incorrect; Try Again; 4 attempts remaining

Part B

Express this amount of energy in

kJ

.

Express your answer using three significant figures.

kJ

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Part C

Express this amount of energy in

Cal

.

Express your answer using three significant figures.

Cal

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Exercise 6.4

A frost-free refrigerator uses 640

kWh

of electrical energy per year.

Part A

Express this amount of energy in

J

.

Express your answer using three significant figures.

2.45

J

SubmitHintsMy AnswersGive UpReview Part

Incorrect; Try Again; 4 attempts remaining

Part B

Express this amount of energy in

kJ

.

Express your answer using three significant figures.

kJ

SubmitHintsMy AnswersGive UpReview Part

Part C

Express this amount of energy in

Cal

.

Express your answer using three significant figures.

Cal

SubmitHintsMy AnswersGive Up

Explanation / Answer

1)

640 kWh

1kWh--> 3.6*10^6 J

640*3.6*10^6 = 23 J = 2.30*10^9 J

2)

2.30*10^9 J

1 kJ = 10^3 J

then

2.30*10^9 *10^-3 = 2.30*10^6 KJ

3)

1 Cal = 4.184 kJ

2.30*10^6)/(4.184) = 549713.19311 = 5.50*10^5 Cal

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