Speed of ball bearing from slingshot using sound delay

[junesmrithi]

Homework Statement

Question: To find the speed of a ball bearing launched from a wrist rocket (sling-shot) you take aim at a 55 gallon steel drum exactly 78 meters from you. You hear the "clunk" of impact 0.7 seconds after you "let fly." If the speed of sound on that particular day is 330 m/s, how fast must the ball bearing be traveling?

 

[andrevdh]

The path of the ball bearing will be parabolic, but if we assume that it was shot horizontally we have that the launching speed $$v_o$$ will be exactly equal to the x-velocity component, $$v_x$$, of the ball bearing.
So if you can calculate $$v_x$$ you have your answer.