Fishing Line Physics: Finding Time and Velocity

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SUMMARY

The discussion focuses on calculating the time and velocity of a fishing line cast at 27 m/s at a 33-degree angle from a 15-meter tall bridge. The user calculated the total time until the line hits the water as 3.74 seconds by breaking the motion into two parts: the descent from the bridge and the fall to the water. The final velocity upon impact was determined to be 22.69 m/s. A suggestion was made to simplify the calculation method, emphasizing that projectiles are only influenced by gravity, not horizontal acceleration.

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  • Understanding of projectile motion principles
  • Familiarity with kinematic equations, specifically x=xo+vot+1/2at² and v=vo+at
  • Basic knowledge of trigonometry for resolving velocity components
  • Concept of gravitational acceleration (9.81 m/s²)
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  • Study the derivation and application of kinematic equations in projectile motion
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  • Explore the concept of vector decomposition in physics
  • Investigate the "tricycle method" for simplifying projectile motion problems
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1. A fishing line is cast at 27 m/s at an angle of 33 degrees above the horizontal from the top of a 15m tall bridge. Find the time until the line hits the water below and find its velocity when it hits.



Homework Equations


x=xo+vot+1/2at2
v=vo+at



The Attempt at a Solution


I first found my component velocities and then the time by using the x=... equation above. I broke it up into 2 parts: the time it took to leave the bridge to the time it was level with the bridge on its downfall and i got 2.94s. Then i found the time it took to go from the point level with the bridge to the water and got .8s. I then added 2.94+.8=3.74s*.
To find the velocity i plugged my numbers into v=... equation above and got 22.69m/s*.

Someone please check and see if I did this correctly! I'm not sure if I was supposed to break it into 2 parts to find the time!
 
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A tip, when you preview the first post it puts the template in again, it helps to edit that out.

As for breaking it into two parts...my high school teacher described it as the tricycle method. There's a simpler way to do this.

However, why does your X component have acceleration in it? Remember projectiles are only affected by the force of gravity.
 

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