PunjabiJatti
Answered

PLEASE help me with these questions as soon as possible i need to turn it in!!!!

A 60 watt light bulb uses 60 joules of electrical energy every second. However, only 6 joules of electrical energy is converted into light energy each second.
a. What is the efficiency of the light bulb? Give your answer as a percentage.

b. What do you think happens to the “lost” energy?

19. The work output is 300 joules for a machine that is 50% efficient. What is the work input?

20. A machine is 75% efficient. If 200 joules of work are put into the machine, how much work output does it produce?



Answer :

a. I believe this might be the answer but
6 J/60 J= .1
.1 x 100= 10%

b. I'm not sure of this question


19. I'm not sure if I did this correct way or if there is a better way (I'm rusty) 
300 J/.50 %= 600
600/100= 6 (answer)


20. (200 J)(.75%) = 150 (answer)
Check:
Efficiency: output/input x 100
150 J/200 J= .75
.75 x 100= 75%

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