Pole Vaulting Kinematics Problem

  • #1

Homework Statement


A pole-vaulter leaves the ground with an upward speed of 9.5 m/s.
(a) How fast is she going when she is 2.0 m above the launch point?
(b) How long is required to reach this height?
(c) Why are there two answers to (b)?



The Attempt at a Solution



Question A and B I don't have a problem with. I worked out A to be 7.1 m/s (2 sig digs) and B to be 0.2 seconds (2 sig digs).

However it is question C I am not understanding. I feel tempted to write "because I can write the answer in seconds or I can write it in minutes". But I feel this is a silly answer, therefore I need help.
 

Answers and Replies

  • #2
CAF123
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However it is question C I am not understanding. I feel tempted to write "because I can write the answer in seconds or I can write it in minutes". But I feel this is a silly answer, therefore I need help.
When the pole vaulter goes up, she must come down.
 
  • #3
When the pole vaulter goes up, she must come down.

So there could be one answer that measures her going up and one answer that measures her going up then coming down?
 
  • #4
CAF123
Gold Member
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So there could be one answer that measures her going up and one answer that measures her going up then coming down?
Yes, depending on what kinematic equation you use you will either get the two solutions automatically or not.
 

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