7. A stereo is able to convert 20% of its electrical energy into sound. If 1000 J of sound energy is produced, calculate the electrical energy used [Show all work].

8. A vehicle is only 18% efficient. How was the other 82% of the energy lost?

What is the electric force acting between two charges of -0.0045 c and -0.0025 c that are 0.0060 m apart? use fe=kq1q2/r^2 and k = 9.00 x 10^9 n*m^2/c^2 a. 1.7 x 10^7 n b. -1.7 x 10^7 n c. -2.8 x 10^9 n d. 2.8 x 10^9 n

Which of the following statements correctly describes a transformer?

If water vapor with the mass of 35.0 grams is cooled and condensed into water in a closed system such as a closed glass jar, what is the mass of the water after the water vapor completely condenses? a) 34.5 grams b) 35.0 grams c) 35.5 grams d) the mass cannot be determined without knowing the volume