Solution - American Association of Physics Teachers
Solution - American Association of Physics Teachers
Solution - American Association of Physics Teachers
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2013 F = ma Exam 32. Jordi stands 20 m from a wall and Diego stands 10 m from the same wall. Jordi throws a ball at an angle <strong>of</strong> 30 ◦above the horizontal, and it collides elastically with the wall. How fast does Jordi need to throw the ball so thatDiego will catch it? Consider Jordi and Diego to be the same height, and both are on the same perpendicular linefrom the wall.(A) 11 m/s(B) 15 m/s(C) 19 m/s(D) 30 m/s(E) 35 m/s<strong>Solution</strong>The wall acts like a mirror for a perfectly elastic collision. In that case, Jordi and Diego are effectively 30meters apart. Using the range formula,we getv 2 =R = v2gsin 2θ,gRsin 2θ ≈ 300 m2 /s 2√3/2v ≈ 19 m/sCopyright c○2013 <strong>American</strong> <strong>Association</strong> <strong>of</strong> <strong>Physics</strong> <strong>Teachers</strong>
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