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Physics 211, Quiz 8

Question 1:

A marksman fires a rifle at a target 200 meters away. The target is at the same height as the rifle. The marksman aims straight for the bullseye, pointing his rifle perfectly horizontal. The bullet leaves the gun at a speed v = 400 m/s.

Where does the bullet strike the target?

  Answer:  The bullet has a horizontal speed 

                v(x)  =  400 m/s

           and so takes 
  
                            200 m
                  t   =   ---------  =  0.5 s
                           400 m/s

           to reach the target.  During that time, the bullet falls
           a vertical distance

        
             (y - yo) =   voy * t  +  0.5 * a * t^2

                      =      0     +  0.5 * (-9.8 m/s^2) * (0.5 s)^2

                      =  (-4.9 m/s^2) * (0.25 s^2)

                      =  -1.2 m

           So the bullet strikes the target 1.2 meters below the bullseye.

Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.