Posted by **Toy** on Tuesday, October 14, 2008 at 3:21am.

calculate the redshift gh/c^2 if h is the distance from the ground to a satellite in low-Earth orbit, 300km. Suppose the "light" is actually a radio wave with a frequency of 10^11 Hz. How many cycles would the transmitter emit if it ran for one day? How many fewer would be received in one day by the satellite? How long did it take the transmitter to generate these "extra" cycles?

- physics -
**drwls**, Tuesday, October 14, 2008 at 4:32am
Since gh/c^2 is dimensionless, it must be the RELATIVE change is wavelength (or frequency). g is the acceleration of gravity at the earth's surface. Plug in the numbers and you get

(delta f)/f = 9.8 m/s^2*300m/(9*10^16) m^2/s^2 = 3.27*10^-14.

The red-shifted frequency will be that times 10^11 Hz, or 3.27*10^-3 Hz. Use that to answer the other questions.

- physics -
**charles**, Tuesday, October 14, 2008 at 10:00am
A hydraulic lift office chair has it's seat attached to a piston with an area of 11.2cm squared. The chair is raised by exerting force on another piston, with an area of 4.12 cm squared. If a person sitting on the chair exerts a downward force of 219 N, what force needs to be exerted on the small piston to lift the seat?

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**drwls**, Tuesday, October 14, 2008 at 11:07am
Please use "Post a New Question" for new questions.

Questions about hydraulic lifts can always be solved by using the fact the

(force)/(piston area0 is a constant for all pistons in contact with the same fluid

- physics -
**Toy**, Tuesday, October 14, 2008 at 12:07pm
where did u get 9*10^16 and how can i answer the questions??? im still confused.. sorry

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