PRINT THIS ANSWER SHEET TO FILL OUT AND TURN IN.

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## Mach Number Worksheet

1. Use the definition of Mach number obtained from the Mach Number slide and the information in the activity to determine the speed of a rocket flying at Mach 3 at sea level. ______________.

2. Convert the sea level static speed of sound, 760 mph, from units of mph to km/hr. ____________________.

3. Let's perform a little study to determine how the velocity of a rocket changes during its flight into orbit. We've installed a small device on the side of the rocket to measure the free stream Mach number. The data is presented below in terms of time after launch and measured Mach number. Convert this data to velocity (km/hr) assuming the speed of sound remains the same as the velocity you computed in problem #2:

 Time s Mach Speed, km/hr 60 1.0 ________________________ 120 2.8 ________________________ 180 4.5 ________________________ 240 6.5 ________________________ 300 9.0 ________________________

4. We know that the temperature and speed of sound change with altitude, so let's correct our data for that effect. We have some additional radar data that gives the altitude of our rocket during its ascent. Use the AtmosModeler simulator to determine the actual speed of sound at each altitude and calculate a more accurate value of the rocket's velocity:

 Time s Mach Altitude m Speed of Sound, km/hr Speed of Rocket, km/hr 60 1.0 1000 ________________________ ________________________ 120 2.8 2500 ________________________ ________________________ 180 4.5 5000 ________________________ ________________________ 240 6.5 15000 ________________________ ________________________ 300 9.0 30000 ________________________ ________________________

5. The RocketThrust computer simulation was used to model the exhaust from the Space Shuttle Main Engine (SSME) nozzle. The exit Mach number is 4.54, and the exit velocity is 12,250 feet/sec.

A. What is the speed of sound in the exhaust (feet/sec)?

Exhaust Speed of Sound = __________________

B. How does that compare with the speed of sound in air at sea level, expressed in feet/sec?

Air Speed of Sound = __________________

C. Why do you think they are different?

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