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Today’s puzzler:

Today’s puzzler: While walking through an open field on a windy day, you accidentally step on a nest of killer bees. In which direction should you run to save your life? Will you be able to run fast enough to escape?

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Today’s puzzler:

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  1. Today’s puzzler: While walking through an open field on a windy day, you accidentally step on a nest of killer bees. In which direction should you run to save your life? Will you be able to run fast enough to escape? The wind is blowing from the east at 4.5 meters/sec (10 miles/hour). Bees have a measured maximum speed of about 8 meters/sec (18 miles/hour). The fastest runners can attain 10 meters/sec (23 miles/hour), most people much less than that. 1) Yes, North 2) Yes, South 3) Yes, East 4) Yes, West 5) No

  2. 1 of 3 • Ball A is launched at 30 deg above the horizontal over level ground. Ball B is launched at 60 deg above the horizontal. They both have the same speed at launch. Their initial velocity vectors are shown. The horizontal distance that B travels before striking the ground is • Greater than that for A. • Equal to that for A. • Less than that for A. • indeterminable without knowing the angle of launch. y B A x 2

  3. 2 of 3 • Ball A is thrown straight upward. Ball B is simultaneously launched at some angle above the horizontal. Both reach the same maximum altitude. Ignoring atmospheric drag, ball B’s flight time is • Greater than A’s. • Equal to A’s. • Less than A’s. • indeterminable without knowing the angle of launch. A B path path 3

  4. 3 of 3 A battleship simultaneously fires two shells at enemy ships. If the shells follow the trajectories shown, which ship gets hit first? A Both at the same time B Need more information Eric Mazur’s Peer Instruction, Prentice Hall, 1997, p. 110. 4

  5. ANNOUNCEMENTS • Join immediately. Enter your student ID number. Power down the responder before returning to the duffle.

  6. PARABOLAS IN EVERY DAY LIFE

  7. 1 of 3 • Ball A is launched at 30 deg above the horizontal over level ground. Ball B is launched at 60 deg above the horizontal. They both have the same speed at launch. Their initial velocity vectors are shown. The horizontal distance that B travels before striking the ground is • Greater than that for A. • Equal to that for A. • Less than that for A. • indeterminable without knowing the angle of launch. y B A x 7

  8. 2 of 3 • Ball A is thrown straight upward. Ball B is simultaneously launched at some angle above the horizontal. Both reach the same maximum altitude. Ignoring atmospheric drag, ball B’s flight time is • Greater than A’s. • Equal to A’s. • Less than A’s. • indeterminable without knowing the angle of launch. A B path path 8

  9. 3 of 3 A battleship simultaneously fires two shells at enemy ships. If the shells follow the trajectories shown, which ship gets hit first? A Both at the same time B Need more information Eric Mazur’s Peer Instruction, Prentice Hall, 1997, p. 110. 9

  10. PROJECTION SCREEN 1 4 1 4 1 4 1 4 2 5 2 5 2 5 2 5 3 6 3 6 3 6 3 6 HAND IN TODAY’S ACTIVITY SHEETS 10

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