# What is the efficiency of the engine?

1. May 14, 2006

### bluemoon

f an engine must do 500 joules of work to pull a 10 kg load up to a height of 4 meters, what is the efficiency of the engine?

So that's
400/50,000

which gives me 0.008

Does that mean the efficiency is 8%?

2. May 14, 2006

### Cyrus

where did you get your numbers from?

50k?

400?

None of this makes any sense.

3. May 14, 2006

### bluemoon

Work done: 10kg*9.8N/kg*4=appx 400J

efficience= work done/500 * 100

4. May 14, 2006

### Cyrus

400J is not correct, please write down the correct numerical value.

Your second line is not correct.

efficiency = work needed ideal/ work actually required

It is always less than one.

5. May 14, 2006

### bluemoon

Okay for my first line, I got 24.5

and I don't know how I'm messing up on my second line. ??

6. May 14, 2006

### Cyrus

where are you getting these number from?

You need to start showing me your work and not just some random numbers you are calling approximations.

7. May 14, 2006

### Gokul43201

Staff Emeritus
Bluemoon : Please write down the equations before plugging in numbers.

Last edited: May 14, 2006