# Artillery Cannon Shoots Down Its Own Shell

An artillery cannon has a muzzle speed (initial shell speed) of 1000 meters per second. It fires its first shell from ground level at an angle of 70 degrees with respect to the horizontal. After reloading, it fires its second shell 30 seconds later at a different angle. The second shell is fired in such a way that it intercepts the first shell in mid air. Determine the angle (in degrees) at which the second shell was fired. The gravitational acceleration is $$9.8 \text{ m/s}^2$$.

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