Fishing Line Physics: Finding Time and Velocity

AI Thread Summary
The discussion focuses on calculating the time and velocity of a fishing line cast from a bridge. The initial calculations involved breaking the motion into two parts: the time to descend to the level of the bridge and the time to hit the water, resulting in a total time of 3.74 seconds. The velocity upon impact was calculated to be 22.69 m/s. Participants noted that the use of two parts for time calculation may not be necessary and emphasized that projectiles are only influenced by gravity, not horizontal acceleration. Clarifications on the correct approach to solving the problem were provided to ensure accuracy.
moondawg
Messages
45
Reaction score
0
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!
 
Physics news on Phys.org
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.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Trying to understand the logic behind adding vectors with an angle between them'
My initial calculation was to subtract V1 from V2 to show that from the perspective of the second aircraft the first one is -300km/h. So i checked with ChatGPT and it said I cant just subtract them because I have an angle between them. So I dont understand the reasoning of it. Like why should a velocity be dependent on an angle? I was thinking about how it would look like if the planes where parallel to each other, and then how it look like if one is turning away and I dont see it. Since...
Back
Top