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?

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

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)

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

Answered by megeliz13 | 2024-06-10

To calculate the efficiency of the light bulb, we can use the ratio of useful energy output (light energy) to the total energy input (electrical energy), and then multiply by 100 to get a percentage. For this 60 watt light bulb, with 6 joules per second converted into light energy, the calculation is as follows:
Efficiency (%) = (Useful Energy Output / Total Energy Input) × 100 Efficiency (%) = (6 Joules / 60 Joules) × 100 Efficiency (%) = 10%
The "lost" energy in the light bulb is mostly converted into heat energy, which is not useful for lighting purposes.
To answer the work and energy related questions:
If a machine has a work output of 300 joules and is 50% efficient, the work input is calculated as follows: Work Input = Work Output / Efficiency Work Input = 300 Joules / 0.5 Work Input = 600 Joules
If a machine is 75% efficient and has 200 joules of work input, the work output it produces can be calculated as: Work Output = Work Input × Efficiency Work Output = 200 Joules × 0.75 Work Output = 150 Joules

Answered by Qwshop | 2024-06-24

The efficiency of the light bulb is 10%. The lost energy typically transforms into heat, which is dissipated into the environment. For a machine with 50% efficiency and 300 joules output, the work input is 600 joules, while a 75% efficient machine with 200 joules input produces 150 joules of output.
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Answered by megeliz13 | 2024-10-02