Posted by **jake** on Thursday, January 13, 2011 at 10:05pm.

I got E) for the first and couldn't figure out the other one. Can any one verify the first and help with the second??

In which of the following processes is there a decrease in the potential energy of the substances involved?

A) a coil spring is compressed

B) two particles of opposite charge are separated

C) photosynthesis produces glucose from carbon dioxide and water

D) liquid water evaporates to form water vapor

E) methane gas burns in oxygen to form carbon dioxide and water

The speed of light is 3.0 x 108 m/s. How many milliseconds does it take for a light signal from earth to reach and return from a satellite that is in orbit 30 miles above the earth? (1 millisecond = 10-3 seconds)

A) 320 milliseconds

B) 16 milliseconds

C) 32 milliseconds

D) 0.32 milliseconds

E) 0.16 milliseconds

No one has answered this question yet.

- chemistry -
**Dr Russ**, Friday, January 14, 2011 at 6:54am
Convert miles to metres

1 miles = 1 609.344 metres

so

distance = 30 miles x 1 609.344 metres mile^-1

=48280.32 m

time taken = distance/velocity

=48280.32 m/ 3.0 x 10^8 m s^-1= 0.0001609 s or 0.16 ms

- chemistry -
**D**, Saturday, February 12, 2011 at 7:50pm
Sorry Doc but the satallite is 30 miles above the earth and the question states there and back. please check again.

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