Calculating Archerfish's Line of Sight Angle in Relation to Squirt Angle

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Homework Help Overview

The problem involves an archerfish aiming to hit a beetle with a stream of water, requiring calculations related to projectile motion. The context includes determining the time of flight, horizontal distance, and the angle of the fish's line of sight compared to the angle of the water squirt.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the calculations for time and distance using projectile motion equations, questioning the relationship between the line of sight angle and the squirt angle. There is also a comparison made to a basketball player's shooting angle.

Discussion Status

The discussion is ongoing, with participants providing calculations and questioning the assumptions regarding the angles involved. Some guidance has been offered regarding the need for accuracy in calculations, but no consensus has been reached on the relationship between the angles.

Contextual Notes

It is noted that the problem assumes the fish is looking at its prey, which influences the interpretation of the line of sight angle.

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Homework Statement


An archerfish hunts by dislodging an unsuspecting insect from its resting place with a stream of water expelled from the fish's mouth.
Suppose the archerfish squirts water with a speed of 2.00 m/s at an angle of 50 degrees above the horizontal, and aims for a beetle on a leaf 3.00 cm above the water's surface.
a. Find the time it takes for the water to hit the beetle; why are there 2 answers?
b. At what horizontal distance from the beetle should the archerfish fire if it is to hit its target in the least time?
c. Find the angle (above the horizontal) of the archerfish's line of sight; explain why the line of sight angle is not 50 degrees!

What I want to know is if the line of sight angle is allowed to be greater than the angle of the squirt?

Homework Equations


3 DVAT formulas

The Attempt at a Solution


After I solved for t (using quadratic formula, vertical acceleration, initial vertical velocity(which I got using law of sines), and delta y), I solved for delta x using the smaller of the two values I got for t (this time is when it reaches .03m high before the peak of the curve). The value I got for delta x was .023 m. I am 95% certain that this a correct value. Then to solve for the angle of the line of sight of the archerfish I used delta x, delta y, and law of tangents and got an angle of 52 degrees above the horizontal. However, the angle of the squirt of water was 50 degrees above the horizontal, and I am unsure if the angle of the line of sight is allowed to be larger than the angle of the squirt of water?
 
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If the archerfish is looking at the beetle, at what angle is his line of sight?
What does a basketball player look at when shooting free throws?
 
J Hann said:
If the archerfish is looking at the beetle, at what angle is his line of sight?
What does a basketball player look at when shooting free throws?
A basketball player would be looking at the net when shooting a freethrow, and the angle of his shot would be above his line of sight, so does that mean that the archerfish's lines of sight can't be greater and the angle of the squirt of water?
 
How would you find the line of sight if you don't know what the fish is looking at?
 
My teacher said it was assumed in the problem that the fish was looking at its prey, sorry, I guess I should have included that
 
RaeZ said:
After I solved for t (using quadratic formula, vertical acceleration, initial vertical velocity(which I got using law of sines), and delta y), I solved for delta x using the smaller of the two values I got for t (this time is when it reaches .03m high before the peak of the curve). The value I got for delta x was .023 m. I am 95% certain that this a correct value. Then to solve for the angle of the line of sight of the archerfish I used delta x, delta y, and law of tangents and got an angle of 52 degrees above the horizontal. However, the angle of the squirt of water was 50 degrees above the horizontal, and I am unsure if the angle of the line of sight is allowed to be larger than the angle of the squirt of water?
I suspect you are just not being accurate enough in your calculations. Keep at least 4 significant figues at each step.
I get a slightly larger number for x.
What do you get for the time?
 

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