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## Homework Statement

An object is flying through the air at M=0.5. The free stream temperature is equal to 180 K. At what speed should the object fly when the temperature is 100 K in order to maintain the same Mach number? (therefore ensuring compressibility effects are the same). What was the speed of the first object.

## Homework Equations

[itex]M=\frac{V}{a}[/itex]

[itex]a=\sqrt{γRT}[/itex]

## The Attempt at a Solution

I've worked out the speed for the first object which is as follows

[itex]a=\sqrt{1.4\times287\times180}=268.931m/s[/itex]

[itex]V=0.5\times268.931=134.465m/s[/itex]

However when I work out the speed for the second temperature using the exact procedure, I get 100.225 as an answer. The answer that has been given is 88.52m/s.