Teaching Physics with the Physics Suite

Edward F. Redish

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The Black Brant

Small rockets have been used to probe the atmosphere for 40 years. Scientific packages in the nose cone of the rocket detect chemicals in the atmosphere and return to earth by parachute. One early such rocket (the Canadian Black Brant VI) is shown in the figure at the right. It was quite small, being only about 9 ft long and weighing about 100 kg. Yet it could climb quite high. Let’s see if it could probe the stratosphere (10-50 km up), which contains the environmentally important ozone layer. Be sure to explain your reasoning for all parts of this problem (except the last).

A. When launched, the Black Brant VI could accelerate upward with an acceleration of 5g for 20 seconds. (For simplicity, take g for this problem to be 10 m/s2.) At the end of this acceleration phase, it what was its velocity?

B. At the end of the acceleration phase, how high up would it be?

C. At the end of the acceleration phase, the rocket just turned off. For how long will it continue to rise? Calculate the total height to which it will rise.

D. Identify two assumptions that we have implicitly made that, if treated correctly, might significantly affect the results we obtained.

Page last modified December 28, 2010: K28