How Does the Archerfish Use Projectile Motion to Hunt?

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In summary, the archerfish uses a stream of water to dislodge insects from their resting places. The initial speed of the water is 2.36 m/sec at an angle of 20.7 degrees above the horizontal. The vertical component of this velocity is calculated to be 0.83. The beetle has to react in order to avoid being hit by the water, which is moving horizontally when it reaches the beetle. The height of the beetle above the fish can be found using the time calculated in part b and the formula d= (vi +vf)/2 x t. The horizontal distance between the fish and the beetle can be calculated using the velocity of the horizontal motion.
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wolves5
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The 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 an initial speed of 2.36 m/sec at an angle of 20.7 degrees above the horizontal. When the stream reachs the beetle a height h avoe the water's surface it is moving horizontal.

https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/Phys1201/fall-evening/homework/Ch-04-2D-Motion/wt-archer-fish/archer-fish.gif

(a) What is the vertical component of the water's initial velocity?

I got 0.83 for part a. I did 2.36cos(20.7)

(b) How long does the bettle have to react?

I don't know what to do for this one.

(c) How high is the bettle above the fish?

Would you use d= (vi +vf)/2 x t. You would use the time found in part b right?

(d) What is the horizontal distance between the fish and the bettle?

I'm confused about this one too.
 
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Very nice picture, indeed!

wolves5 said:
(a) What is the vertical component of the water's initial velocity?

I got 0.83 for part a. I did 2.36cos(20.7)
You calculated with sine instead of cosine, I am afraid.

wolves5 said:
(b) How long does the bettle have to react?

I don't know what to do for this one.

Read the problem, the water stream is horizontal when it reaches the beetle. What is the vertical component of velocity there?
How do you get the vertical component of velocity in terms of time?

wolves5 said:
(c) How high is the bettle above the fish?

Would you use d= (vi +vf)/2 x t. You would use the time found in part b right?

What are vi and vf? Take care, this is a two-dimensional motion, you need to treat the horizontal and vertical components separated. And yes, you can use the time you got in part b.

wolves5 said:
(d) What is the horizontal distance between the fish and the bettle?

I'm confused about this one too.

This is projectile motion and it can be decomposed into a vertical motion and a horizontal one. What is the velocity of the horizontal motion?

ehild
 

What is two-dimensional kinematics?

Two-dimensional kinematics is the study of motion in two dimensions, typically involving the analysis of an object's position, velocity, and acceleration in both the x and y directions.

What are the basic equations used in two-dimensional kinematics?

The basic equations used in two-dimensional kinematics are the equations of motion, which include the equations for displacement, velocity, and acceleration in both the x and y directions. These equations can be derived from the fundamental equations of kinematics, such as the definition of velocity and acceleration.

How is two-dimensional kinematics different from one-dimensional kinematics?

One-dimensional kinematics only involves motion in a single direction, while two-dimensional kinematics involves motion in two perpendicular directions. This means that in two-dimensional kinematics, there are two sets of equations for position, velocity, and acceleration, one for the x direction and one for the y direction.

What are some real-world applications of two-dimensional kinematics?

Two-dimensional kinematics is used in a variety of fields, including physics, engineering, and sports. It can be used to analyze the motion of objects in projectile motion, such as a ball being thrown through the air. It is also used in the design of structures, such as bridges and buildings, to determine the forces acting on them.

How is two-dimensional kinematics used in video game design?

In video game design, two-dimensional kinematics is used to create realistic movements and animations for characters and objects in the game. The equations of motion are programmed into the game to calculate the movements of the objects based on user input and the laws of physics, creating a more immersive gaming experience.

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