Find the total distance travel

  • Thread starter jack911
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  • #1
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Homework Statement


the following is a equation to find the displacement of a particle. i've found it is instantaneous at rest at t=5. now need to find the distance travelled between 0 to 10s.

i found distance travelling between 0 to 5 s is 7.5

but no idea how to find distance travelled between 5 to 10s...please help.


Homework Equations



s=0.7t^2-0.1t^3+0.5t

The Attempt at a Solution



32.5m
 
Last edited:

Answers and Replies

  • #2
Tom Mattson
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You don't need to know when the velocity is zero to solve this, you need to know at what time [itex]T[/itex] the displacement is zero. Then the total distance traveled is [itex]|s(T)-s(0)|+|s(10)-s(T)|[/itex].
 
  • #3
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yes i use


|s(5)-s(0)|+|s(10)-s(5)| = 7.5+32.5=40


but the ans is 40 instead of 32.5
 
  • #4
Tom Mattson
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That's no good. The displacement isn't zero when t=5.
 
  • #5
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thanks i got the ans but i wonder why we have to know what time the displacement is zero??i cant get it~.~
 
  • #6
Tom Mattson
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You need to know when the displacement is zero because after that time the displacement becomes negative (and distance is never negative).
 
  • #7
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i get it but i wonder can i do it with find t when v=0? because your method seem not suitable for finding distance between t and t1(where t and t1 are the time when s=0)

can you please point out my mistake in the following equation?

|s(5)-s(0)|+|s(10)-s(5)| = 7.5+32.5=40

thanks a lot:)
 

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