Dimentional Anaylsis: Solving for Revolutions

[valerieangel]

NASA's Cassini mission to Saturn released a probe on December 25, 2004, that landed on the Saturnian moon Titan on January 14, 2005. The probe, which was named Huygens, was released with a gentle relative speed of 31 cm/s. As Huygens moved away from the main spacecraft , it rotated at a rate of seven revolutions per minute.

How many revolutions had Huygens completed when it was 160 yards from the mother ship?


I know the answer is 55 rev; however, I got a completely different answer. I solved for the answer this way:

160yd*(3ft/yd)*(12in/ft)*(2.54cm/in) = x

I then divided x by 31 cm/s, and multiplied it by 420 rev/s.


Any help or advice would be much appreciated.

 

[Muphrid]

How can something that does only 7 revolutions in 60 seconds do 420 revolutions in 1 second?

 

[valerieangel]

How can something that does only 7 revolutions in 60 seconds do 420 revolutions in 1 second?

You're right. I don't know what I was thinking! I did figure out that I needed to divide 7rpm by 60s and multiply that number by 471.948s, which gave to 55rev.