Falling Bodies

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In the IGCSE Physics book by Tom Duncan and Heather Kennett, Chapter 24, page 111, question 4:

"A Gun pointing Vertically upwards is fired from an open car B moving with uniform velocity. When the bullet returns to the level of the gun, car B has traveled forwards to point C and another car A has reached the position occupied by B when the gun was fired. Are the occupants of A or B in danger?"

I Believe there is a mistake. the answers state that Car B is in trouble from the falling bullet, however i find no proof for this. from what i can tell car A is in trouble as air resistance and wind direction are negligible. If the bullet travels vertically upwards, does that not mean the bullet should travel vertically downwards? Could someone elaborate? 

Posted Tue 17th July, 2012 @ 10:36 by Jason Taylor

3 Answers

  • 1 vote

you can use resolution of forces to decide the answer. if the bullet is fired upwards with the car travelling at a constant velocity, that mean that the velocity does not affect the movement of the bulet. you resolve the accelation of the bullet upwards into two components, vertical (V sin theta) and horizontal (V cos theta) components. than after gainin those reolutyions, you can use pythogras' theorem to find the resultant force...... that means that car B will be in trouble not car A.

Answered Tue 17th July, 2012 @ 12:02 by MAXDEE IZY
  • 0 votes

Ah, okay. However how am i to work out those variables when non are given? No measurements of any kind are given. 

Answered Tue 17th July, 2012 @ 12:25 by Jason Taylor
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if you knw that the verticall component is V SIN THETA, and the hrizontal component is V COS THETA, then you can find the direction of the resultant force by drawing a free body diagram.......  you dont need figure to figure it out that the people in car B will be in trouble.... they are onyl testing if you know the concept of resolutin of forces,...... i guess you did that ryt???????

Answered Tue 17th July, 2012 @ 18:16 by MAXDEE IZY